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Dumb question. The heater bypass you are are describing is mounted up front, bypassing just the heater matrix, dropping the vent temps about 5 deg.

Looking at the diagram, and not the car, it seems like it would not be that difficult to move the bypass back to the engine bay, and not run hot water through the side pods and/or the heater core.

What am I overlooking?
 

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Been fighting the heat issue. On any day, the interior vents were nowhere near ambient temperature. The only two ways the car was comfortable was to either run the AC or turn the heater to the Defroster and keep the top off. Did some playing today and here is what I found.

1. My heater flap never closed fully. I would cycle the flap through and it never closed that last 1/4 inch. This always let heat in the system, and I am pretty sure that the flap vs heat ration is non-linear. Lots of heat with little opening, not that much more heat with lots of flap opening. From the experimenting I did, the temperature control knob only controls the position of the flaps. Didn't check with the AC button pushed, but I suspect the same is true.

2. thermocouple that should be touching the A/C condenser, to prevent icing, was about 1/2inch off the condenser! This may have been caused by the fact that there was nothing securing the thermocouple to the mounting bracket.

Here is what I did.

Added the heater by-pass. This doesn't fix the heater flap issue, but at least the heater core is not hot now. Did a quick test drive and now there is no temperature change at the vents if you adjust the temperature knob from full counter clock wise to full clock wise! This is good.

Zip tied the thermocouple to the mounting bracket, and adjusted to touch the A/C. This can only help.

I was looking at adding the vent tubes modification to vent air near the master-cylinder and made a big discovery. Either my my car is missing something our we all are missing something!

I was trying to think aerodynamics and see where the best place to get cool air into this area was and then I noticed it. The problem is not getting the cool air into this area, its keeping the hot air out. Normal workings are: The air comes in the grill of the car, up through the radiator, and then most of the air goes out the vents on the top of the clam. BUT a bunch of the hot air follows up the central spine of the clam, the painted part that is directly below the windshield wiper that divides the two grills, past all the heat shields, and dumps into the area above the heater box & the foot box. Didn't add the 2 1 1/4inch tubes to try to counter act the 6+ inches of hot air being injected in the same area. To see what I am talking about, take off one of the front access panels and follow from the wiper to the radiator via the center spine.

Am I missing a heat shield that goes directly underneath the center spine? I looked up the parts manual and found the left and right heat deflector, (46.01, 19 & 20), but no center deflector. Is my car missing this?

As a test i am using some masking tape to block this area off and taking the car out for a spin.
 

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Did about 20 miles of "testing" and here is what I found. Out side temp, as per local TV station 88 deg. Engine temp as per dashboard 194.

Before "Testing" After Testing
Dash Temp "R" in airbag pass side 102.1 109.6
Dash Vent Output Temp By-Pass on 110.3 112.2
Dash Vent Output Temp By-pass off 110.3 145.7

Thanks Tony. Now I am going to fabricate a heat deflector for the center spine.
 

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Michael,

I agree. Its just that I found, on my car anyway, a BIG place where the hot radiator air can heat soak the top of the heater box and the fount of the peddle box.

There was a 4 1/2 by 6 inch hole for the hot air from the radiator to blow directly on the big hose that connects the heater box to the dash board.

Doug
 

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dang, there goes my aftermarket get rich scheme. That black piece is exactly what my car did not have, and I fabricated today. On the dinner run with the lovely bride, the car was pleasant to be in, not the mobile sauna I have come to know.
 

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the one I made:

The bottom of the deflector was touching the radiator
The left and right side actually overlapped the two heat deflectors directly under the access pannel
The top had a tong that I taped up to the bottom of the central spine on the clam. I can take a picture tonight if ya want.
 

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There are some pics of my solution.

The top pict is the foam piece as I cut it out. I uses some GM under hood sound insulation that is about 3/4 of an inch thick.

The three fingers go to the top of the install. The thick middle finger is taped to the underside of center spine. The two smaller fingers go on either side of the spine, just above the rain gutters (dont block the gutters). The bottom tucks in behind the back of the radiator

The next pictures just show the piece installed. I circled the foam piece, just because.
 

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You bet you can add it. Glad I could give back something.
Score now Doug 1 LotusTalk 999,223
 

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As an option. If you have problems finding the vacuum solenoid, or just want a lighter less complicated solution. An aquarium air valve is a $2.00 workaround. This is the brass valve used to limit air supply, can be found any any WalMart/pet store....
 

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