2007 Exige AC/heater rework - Page 2 - LotusTalk - The Lotus Cars Community
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post #21 of 40 (permalink) Old 02-23-2016, 08:18 AM Thread Starter
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Oh the silicone hose seems to add about 3 percent more flow, but it is hard to say as the diverter assembly seems to be the main flow impediment
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post #22 of 40 (permalink) Old 02-24-2016, 06:33 AM Thread Starter
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Took some additional measurements yesterday, the output of the floor vents when the knob is set to full face vents is about 1/2 of what it is when it is set to floor vent alone. For reference the flow is about 22 cfm on high fan 19 on medium and 16 on low.

I get repeatable measurements so while I do not at all trust the absolute numbers or a comparison between different vents[dash vs floor] the numbers one setup vs another on a particular vent is accurate.
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post #23 of 40 (permalink) Old 03-02-2016, 09:33 AM Thread Starter
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So, testing the fan on the bench I underestimated how much more current the fan draws wide open than when it is flow restricted. The larger resistors are not required, and probably not the heatsink either [lucky thing I didn't have to pay for it]

Pictured are the essentially finished cover installed. I edged the cover with 3/16 soft foam then insulated the underside with the foil faced foam, and IMG-1068 is of the foam placed where the cover will contact it. You can see where I measured and marked a line around to follow.

I insulated the diverter assembly, since it is just as exposed as the hose. I also sealed the edges as they leaked a bit, and every little bit helps.

I tested the fresh air door sealing, and there is a small amount of airflow when pushing the output of a big shop vac up to the intakes in the nose and checking in the footwell vents. This only happens on the passenger side where I added cutouts to the recirc plenum, so I think the flow would be very low if those were not there. At any rate it is small and the fan on low would more than compensate.

Also tested the small opening I added in the cover for the fresh air flap and it does blow a small amount of air up to the area above the heater box, which should flush that area and keep it coolish. It is a PITA to detail, so I think I would probably seal that flap if I did it again as it is probably the source of the air coming in the footwell

I also added a square of 1 inch thick filter foam to the front side of the fan to keep the sand out of the heater box. I tested it in place and the grill on the fan is enough to keep it from sucking into the fan. It is coarse very low restriction so it barely even tries to stick to the fan when it is running

Has anyone got the sizes for the AC orings?

Useless auto parts store sells a whole assortment,of the wrong sizes.
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post #24 of 40 (permalink) Old 03-02-2016, 09:45 AM Thread Starter
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The receiver drier shown is one I purchased that is about 1/2 inch shorter than the stock, and I had to subtly twist the ac hose to get it in. YOu could use the stock drier, it would just have to move towards the back of the car a few inches, meaning actually bending the ac lines[which you should use a bender for as they might kink. It would place towards where my resistors are mounted, but I have already determined that the heatsink is not required it would not be a problem other than fabbing a new mount[which I need to do anyway]n The wiring is more in the way than I anticipated, I am going to re cut the ty wraps and try routing the AC lines first to see if it all fits together neatly
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post #25 of 40 (permalink) Old 04-17-2016, 05:12 PM Thread Starter
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Trying to get things right I have spent more time than I anticipated....
Vintage air 12x24 condenser, p/n 037033 price $139 mounted with cold side down[as opposed to stock] with some simple standoffs, small l brackets for the fans, and some g10/fr4 upper brackets

put a strip of foam so the fans energy isn't wasted
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post #26 of 40 (permalink) Old 04-17-2016, 05:32 PM Thread Starter
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Vintage sells 12 inch ubend solid lines that I used to route the lines out from the condensor

They also sell EZ clip hose[an Eaton product]

Summit carries all the fittings and clips[buy extra clips, see if you can borrow the tool] but not the hose which I will yell at them for, because it is so cheap they should carry it in 3 or 6 foot lengths

part numbers:
#6 hard line 12512VCL $10
#8 hard line 12513VCL $10
45 deg #8 fitting 347280VUR $20
straight 8 fitting 347180VUR$20
[2] straight #6 fittings 34160VUR $17

[4]#6 clips 347962VUR $.60
[4]#8 clips 347982VUR#.60
[2]#6 cage 347960VUR $1.10
[2]#8 cage347980VUR $1.10
#6 hose 318600 ~$4 per foot
#8 hose 318800 "


I heat shrunk the ends for neatness and to prevent chafing

you can see the simple bracket i made for the receiver drier since I moved it slightly from the stock location, it hangs of my resistor heatsink, or should I say resistor rain guard as when installed the fan does not draw enough current to get them as hot as it did on the bench. I already had it installed so oh well....next tim eI would just screw them to the sheet metal panel
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post #27 of 40 (permalink) Old 04-17-2016, 05:43 PM Thread Starter
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Held vacuum for a week.....

So I fired it up and put some R134 in it and viola, cold air

now it is only 68 in the shop, but I've got 41 degree air out the vents and the compressor shuts off no doubt from the thermostat, as it is not under or over pressure. That should mean that up to a point as it gets warmer it will still pump out pretty cold air until the pressures make it shut off.

If it makes sense to insulate the hose, insulate the diverter assembly, and some of the firewall

The hose was cold to the touch and may be leaking, the silicone is slightly larger than the corrugated so I have to fight it off and seal it a little better.

The electronic valve runs hot to cold just fine, right from the factory knob, no extra wires in the cabin.
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post #28 of 40 (permalink) Old 05-08-2016, 03:41 PM Thread Starter
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Tomorrow the guys are going to put the film on[front clam was painted to fix a few nicks and, err the damage from removing the starshield]. Hopefully the high quality paint and and better film coverage than factory will mean I will not be doing this again soon. Maybe it will eventually get hot enough to test the AC. At any rate now I will be able to drive it again. Spring is slow in coming

The radiator 'air deflecting panels' allow air to flow between them and the clam into the area above the heater. I added weatherstrip to the area . Also there was no center block, so I created one.

I am thinking I will measure the temp under the access panels and see if it is particularly hot, if so I may weatherstrip the leading edge of the access panels
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post #29 of 40 (permalink) Old 05-22-2016, 07:57 AM Thread Starter
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Heat works great.....cool air from vents when fresh air door is open......[so little heat gain from surroundings]

waiting for hot weather....

Last edited by exigegus; 05-22-2016 at 08:27 AM.
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post #30 of 40 (permalink) Old 05-25-2016, 11:29 AM
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Good write-up of your work. I'd strongly recommend adding 3M crystalline to the windshield if you want maximum cabin cooling.
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post #31 of 40 (permalink) Old 05-25-2016, 12:27 PM
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This entire thread is so over my head, just wish I could drop my car off to you and have the same thing done. Awesome thread man!!
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post #32 of 40 (permalink) Old 05-26-2016, 07:17 AM Thread Starter
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Well, it is all Bull hockey until the weather gets hot and I can see if it works or not.
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post #33 of 40 (permalink) Old 05-28-2016, 02:46 AM Thread Starter
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Yesterday

Max out door temp measured: 82 [seems high] mostly mid 70's, bright sun

highway, 3500 rpm

vent temps: cycled consistently between 39 and 46 degrees.

had to turn vents away from my hands cause I was freezing. Normally would have turned the fan down, but hey it is science

Today is supposed to be hot but I have things to do, hopefully I will get time to do more testing....................
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post #34 of 40 (permalink) Old 05-28-2016, 11:21 AM Thread Starter
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Outside temp 83-87 sunny

swapped thermometers, digital one was moving around inexplicably

vent temps on highway 47 degrees

cabin temp down to 74

knuckles still get cold occasionally

left idling in hot sunny parking lot. 5 minutes, vent temps to 60, cabin temp 81, moving in traffic instantly recovered to mid low 50's cabin to 77

I know, it is not 'hot' yet, but I will say, subjectively, this is completely normal AC behavior for a regular car. Most of the time I would have turned the fan down from high, but one must suffer....
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post #35 of 40 (permalink) Old 07-06-2016, 01:04 PM
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Outside temp 92+
Relative humidity was forecast as high 30's, so only moderately humid.
Fluke DMM with thermocouple attachment, ice point referenced this afternoon

vent temps on highway, 3500 rpm

44 degrees


interior temps 72 degrees

still hitting the thermostat [vent temp will drift up to 51 degrees for a few seconds then moved back down and stay at 44, even 43 degrees] so I have not actually reached system capacity. Happens every ten minutes or so with fan on high. More often when fan is on medium. I would say that the duty cycle means at this temp with this interior temp it is at 90% capacity


I say: SUCCESS!!!!

I have virtually zero doubt that the system as currently configured will keep the car comfortable at least to 100 degrees.

After taking my measurements I turned the fan down to medium because my hands were cold. Cabin temp went up a few degrees, maybe 74.


After sitting windows closed in a hot parking lot for 1 1/2 hours[while I had one celebratory beer] the pictured thermometer read over 110 degrees, rolled drivers window down for about 1/8 mile, closed, car was comfortable in about 1 mile, so pulldown is pretty fast. I anticipate at higher humidity pulldown will be slower but the system is now tight enough it should not significantly affect static performance.

Car has no window tint.

When I did the work I moved the thermostat closer to the evaporator. I think this is not necessary, in fact it is my opinion that one could defeat the thermostat with the fan on high[one relay]

I am going to post a victory thread since this one has gotten pretty long and dense

Yes this is still me , new ID for new password.........
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post #36 of 40 (permalink) Old 07-14-2016, 07:39 AM Thread Starter
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i have to say I am appreciating the function of the electronic hot water diverter valve. On the moderate days I can bleed in some heat to temper the AC as it was intended and I think it operates more subtly than the original would have. Since when you half open it the door is half open and the valve is half open it is just feeding a little half warm air in.
kinda like a real car.......
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post #37 of 40 (permalink) Old 03-24-2017, 06:11 AM Thread Starter
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Quote:
Originally Posted by exigegus View Post
To the right of the duct entry[as you are standing in front of the car looking at it, left side in standard car parlance] you will see the small rod coming forward and attaching to a small plastic lever attached to the heater door[which you can see inside the duct opening as a steel bar passing across the bottom] I used two small screwdrivers to pry the plastic lever away from the flat end of the metal rod, and as soon as there was a little space I used them to work between the metal end and the clip , since I was nervous of breaking the plastic arm. Eventually the clip broke, they should be a hardware store part.


[edit]

A bit of gorilla tape should hold it open for the time being. the rod seems to harmlessly move around when detached, may need something to stop it rattling when actually driving
Update:

So the tape let go after a few months, and in the fall I realized I could not get the heater off of defrost, so upon examination the lever wedged itself under the heater flap actuator and the servo is not strong enough to pull it out.

So, don't do that.

I spent a stupid amount of time sure I could come up with an elegant solution that both keep the heater flap open and allow the rest of the system to do its thing. Made several complicated looking brackets, then realized I was overthinking it.

Pictured is a small sheet metal strap with two holes in it. A #6 SHC screw pushed through it, then a nut to retain it while assembling. The screw goes through a small hole drilled in the end of the heater flap actuator[with a drill in a dremel] The screw hits the front of the diverter assembly preventing the actuator from closing. Once pushed into place it is prevented from falling out by the end of the pedal box. The arm coming forward from the face/defroster diverter is screwed loosely to the other end of the strap with a hex head M4 screw and an elastic stop nut. The arm now moves as it did but does nothing, just rotates the strap back and forth. It can no longer become wedged. The total travel of the arm is a bit over an inch, so the strap needs to have the holes far enough apart that it can travel that distance without binding.

This is easily reversible by grabbing the SHC screw with extended needle nose pliers and pulling it out, removing the strap and placing the arm back on the peg and putting a pushnut back on it. That would be the hardest part on the Exige, as there is little access.

There is another style diverter assembly with round rods which would require a different mod, but since the arms on that one are easier to snap on and off, one could remove the arm completely, and then restrain the heater flap actuator, or add a longer arm, with no bend on one end with piece of spring on it like Mcmaster Carr p/n 9663k53 so the spring always keep the heater open

BTW i barely missed the heater flap being closed in the coldish weather. I think tightening up the front of the car helps there, there is no cold air infiltrating so the face vents do better work and your feet still do not get cold.
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post #38 of 40 (permalink) Old 04-01-2017, 01:33 PM Thread Starter
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While finishing up i decided to do few more things.

First, I had added a .5 ohm resistor in series with the low speed circuit, and it still was not slow enough.

I replaced it with a 1 ohm[this time not from amazon] so the total resistance in low fan speed is 1.54 ohms

Second I was looking at the wire sizes and thinking of the heat that can come off of the resistors. Then I was looking at the big battery posts sitting right there doing nothing. I bought a little fused relay on Amazon, and ran some nice teflon insulated 14 ga wire over to the posts, both power and ground. So for high speed the dash switch fires the relay and uses pwoer straight from the battery posts. Or so it should be. Wierd things happened, the fan would run in fast speed on low, or even off, or even with the car off[!!]

So I investigated, there must be some voltage leaking in the switch through the low speed circuit, because detaching that wire stopped the funny business. I put a diode in the low speed circuit and it is perfect.

My little air flow meter says 5 percent more air relay vs no relay. Hey I'll take 5 percent for about 8 bucks.

I also took the time to move the a/c thermostat away from the evaporator. Air temp at the vents is running at the very best high 30's, other cars can be easily low 30's with no freezing. I am convinced that the freezing problem was related to a combination of Lotus restricting the recirc vents and letting a lot of leakage of exterior air in to the system. Plus when it kicks off you get that damp air smell, telling me it is too warm. I also happen to have a Vintage Air adjustable thermostat kicking around so I poked that into the air trunking and can use it to override the stock thermostat if I think it is still too warm, or to substitute if it is too cold, by disconnecting the factory one.

Wouldn't have bothered with any of this if I wasn't in there playing with the pedals, but I am committed to this science project so why not

https://www.lotustalk.com/forums/f259...usions-375169/

Last edited by exigegus; 04-01-2017 at 02:14 PM.
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post #39 of 40 (permalink) Old 05-25-2017, 11:12 AM Thread Starter
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So to follow up on the thermostat, we haven't had consistent hot weather but we had a few days of 80's and 90's. I had set the Vintage air thermostat to give me 33-34 degree air out the vents.

Works well. You get the freezing cold air feeling that is so nice on a really hot day. I would suggest anyone to replace the factory thermostat with this one:
vintage air:
11013-VUE (Rotary 18”)

Mine is just working in parallel with the stock one, so if it had not worked out it was just a few minutes to remove it.

other part numbers:
11092-VUT (Rotary 48”)
11090-VUT (Lever 42”)
these have longer probes so you could theoretically mount it in the cabin if you chose.

I don't know what the Lotus upgrade thermostat does. If it allowed lower evaporator temps, it would be a cool setup[hah]
I suspect it does not as it was a solution for evaporator freezing

One caveat, I 'might' have seen freezing, when I left work to head out of town. By the ocean here it was not that hot, and I put the fan on medium. Well, halfway to the hell that is 'up the line' [local slang for up rt 128, inland, IOW hot] it felt like I wasn't getting enough airflow. I put it on high and it seemed to be fine in a few minutes. I will try messing with it this summer when we get more consistent hot weather, but it is probably wise if you mod your system to give you colder air that you always run it on high to begin with until the air is dehumidified. With the stock thermostat giving me 42-46 degree at the coldest, one is not tempted to put it on anything but high in the beginning, and on high I have seen it take over 15 minutes to hit the thermostat for the first time.

Anyway I will check back in in the hot weather to see if it actually has any icing issues. I may try for even colder vent temps just for fun, I mean, why not be silly
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post #40 of 40 (permalink) Old 08-29-2018, 03:27 PM Thread Starter
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So a follow up after over a year.

The adjustable thermostat may be a good idea, but it started causing icing all the time.
The stock thermostat functions acceptably, but when it turns off you get that damp smell, I think it is too high, but I have to wait until I get some time to set it up close to the evaporator to see if I can tune it.

The Exige is really tight without the nose off, so I may have to wait some time before I play with anything seriously
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