The Lotus Cars Community banner

1 - 17 of 17 Posts

·
Registered
Joined
·
99 Posts
Discussion Starter #1
Hello All,
As the weather warms and our cities burn what better time to go out for a drive than now? That is, unless you don't have cold A/C. Though in NC in June/July, I try to limit my outings to mid 80's max (cool mornings and nice sunsets) anyway and the drive with the widows down and top popped is pleasant enough but still would like to have working cold A/C. My S4s is one of the handful that is still R12. Through my research on this and other forums It appears that a PO has installed the convenient right angle adapters for the low pressure lines so a refill should be pretty easy ( I will post a pic when I'm back home for confirmation) but before I do that I want to eliminate any suspicion I have of a stuck/defective temperature control. One of the first things I did when I bought the car was to troubleshoot the the "No Heat" strike from the PPI. Replaced the vacuum pump, and dug in behind the radio to free up a stuck vacuum switch. All that resulted in return of heat so the heater matrix is good (thank god).
Of course, the last thing I need is heat, I may need it on a cool fall evening once or twice. I'm just thankful that the heater matrix is working and not something that needs to be addressed.
Anyway, the reason I suspect the temperature is that heat is really hot and you cannot make it anything other than really hot. It doesn't matter if I put the temperature dial all the way to the left/red or right/blue. Now I understand that the "heat" comes out of the windshield and footwells and the "cool" comes out of the face and dash vents and never two shall meet but you would think adjusting the dial would at least turn it from frying pan to sauna to warm bath. Correct me if I'm wrong. If the forum deems it so, I will sacrifice my weekend and my knuckles to appease the monster behind the dash. I have to the binnacle off to get at the busted odometer anyway so...

Thanks
Rob
 

·
Wingless Wonder
1988 Esprit Turbo
Joined
·
5,940 Posts
Hi Rob,


At first glace, it sounds to me as if your vacuum actuator is stuck, again. (This time, on HEAT) If it is easily accessed you could take a look through the binnacle, maybe. (I've never done it that way, though.)

However, bear in mind that Esprit heat is regulated by coolant flow through the heater matrix, not via an air-mix door as on modern cars. So, it takes a minute or two or three to cool off even after the warm coolant stops flowing. Verify that the hot air isn't a result of your modern expectations.

You should get cool air out of the defrost & footwells with the temp control all the way clockwise (6 o'clock position). See if it stays cool with the temp on cold from the beginning of your next drive.

For you folks who grew up in the digital-clock age, '6 o'clock' is pointing downward. :whistle:
 

·
Registered
Joined
·
3,419 Posts
Does the compressor clutch activate to run the compressor when you turn on the A/C? If not, you are probably low on refrigerant. If the clutch does "pull in" does the line coming out of the compressor get hot and the one going in get cool? On some cars there is a little window on top of the dryer. When the compressor is going you might see bubbles in it go by. My guess is you have more than one problem. Low refrigerant and a problem with the vents and a problem with the heat. Once the heater valve sticks it is prone to getting stuck again. Start by verifying vacuum to the reservoir. To shut the hot water to the heater core you can just clamp one of the lines going to the heater core temporarily.
David Teitelbaum
 

·
My car sneezes
Joined
·
656 Posts
Does the compressor clutch activate to run the compressor when you turn on the A/C? If not, you are probably low on refrigerant. If the clutch does "pull in" does the line coming out of the compressor get hot and the one going in get cool? On some cars there is a little window on top of the dryer. When the compressor is going you might see bubbles in it go by. My guess is you have more than one problem. Low refrigerant and a problem with the vents and a problem with the heat. Once the heater valve sticks it is prone to getting stuck again. Start by verifying vacuum to the reservoir. To shut the hot water to the heater core you can just clamp one of the lines going to the heater core temporarily.
David Teitelbaum
Good advice. FYI, every receiver/drier I've seen installed on an Esprit has the sight glass but the protective sticker needs to be removed.
 

·
Registered
Joined
·
99 Posts
Discussion Starter #6
Thanks All.
I will dig into this weekend if I have time.
Pretty sure the compressor clutch is engaging but really hard to witness it with the positioning of it.
The vacuum powered flaps are working. Is the thermostatic water valve also vacuum powered?
Also, to check my understanding, the AC evaporator and the heater matrix both live in the same box with the cabin blower, correct? So if the temperature control is not limiting hot water to the heater matrix then a functional AC system will still be fighting the heat?
 

·
Wingless Wonder
1988 Esprit Turbo
Joined
·
5,940 Posts
So if the temperature control is not limiting hot water to the heater matrix then a functional AC system will still be fighting the heat?
With the MODE dial on INTERIOR, the A/C will de-humidify the air going to the defrost and footwells. Yes, it will 'fight the heat'.

So yes, if the hot coolant is circulating through the heater, the temps coming out of those outlets will be warm.

The face-level vents should still be cold, though...the air temp from those is not dependent on the heater matrix in any way. See Service Notes section PD3, page 6.

1265451
 

·
Registered
Joined
·
3,419 Posts
According to Carbuff's post # 3 the heater control is NOT vacuum. While it may be difficult to actually SEE the clutch, if you feel the lines going to the evaporator coil in the passenger footwell, one should be warm and one should be cold As for the heater core, if you can feel the lines going to the heater core, if the valve is closed, the hoses should not get hot. If the flaps are working, the air passing through the evap coil doesn't pass through the heater coil when you run the A/C and set the air to come out the face level vents. If it is realy hot you should be on RECIRC.
David Teitelbaum
 

·
Registered
Joined
·
99 Posts
Discussion Starter #9
Thanks!
Here is a pic of the engine bay side.
1265606


I don't witness any bubbles through the drier.
Can I access the evaporator lines in the footwells?

Rob
 

·
Registered
Joined
·
99 Posts
Discussion Starter #10
Is the insulation around the lines going to the evaporator supposed to look like this?
1265611
I’m thinking the answer is “no”
🙄
 

·
Registered
Joined
·
3,419 Posts
If the clutch is engaged and one line is hot and the other is cool, you have enough refrigerant to at least get some cooling. If you are not seeing bubbles you probably have plenty anyway. Yes the cork insulation will look messy but that is OK. You need to make sure the actuators are moving the flaps correctly so you get cool air out the face vents and you need to get the heater valve to close if it is not doing it. Verify vacuum and check that the mode switch is moving the cams and controlling the actuators. Those do look like the service ports but there should be dust caps on them to keep the dirt out.
David Teitelbaum
 

·
Registered
Joined
·
99 Posts
Discussion Starter #12 (Edited)
Thanks Guys
I forgot to mention the lines going to/from the heater core are almost too hot to touch regardless of temperature dial position. I will clamp that off next and see what I get.
By the way, I'm going to hijack my own thread. Please take another look at the footwell picture. Is it normal for factory black carpets to start wearing away to reveal tan carpet? I doubt it. This and other more obvious examples lead me to believe a PO spray-dyed factory tan carpets to black. Likely to hide a stain...
Also, there is a UK company that sells replacement carpet sets for 88-92 Lotus Esprit Carpets. But I don't see what would make them not fit the S4...They have the "saddle bags" at the inner knee placement instead of behind the seats but that shouldn't be an issue. I am going to email them and find out.
Thanks for all the help and enjoy the holiday weekend.

Rob
 

·
Registered
Joined
·
906 Posts
Rob

I am interested in an S4 carpet set too. I wonder if the shipping is really advantages maybe we could have two kits shipped to your house and I could pick one up. Maybe not worth the hassle, let me know what shipping works out to be to your place, I am sure it will be similar to Atlanta.
 

·
Wingless Wonder
1988 Esprit Turbo
Joined
·
5,940 Posts
Is Coverdale the same carpet source as Steve Margary? His carpet sets have gotten RAVE reviews on TLF.

Here's his Facebook carpet page:

Steve Margary carpets & flooring LTD


 

·
Registered
Joined
·
99 Posts
Discussion Starter #15 (Edited)
Update:
The Temperature dial is definitely not working. The steel cable is connected on both ends and not snapped. It seems though that the green cable sheath is not anchored behind the radio and is just flopping around in there. That issue is for another day as I can access the valve and manually open and close the valve. shout out to this thread from 2017. so with the matrix shut off and the lines cool, I am still at best getting coolish-warm air.
Compressor is working properly as stated above. Hot water to the matrix is shut off. I decided to put a meter on the leads to the drier. Nada. It seems that the receiver/drier is a passive device but there are electric leads attached 🤷‍♂️.
 

·
Registered
Joined
·
99 Posts
Discussion Starter #16
Please help me interpret this from the manual.

A.C. & Radiator Fan Control (see sheet 8)
The air conditioning uses a control system which includes energisation of the compressor clutch to modulate cabin temperature. The driver operated a.c. temperature control in the cabin is linked to a thermistor control unit which compares demand and supply temperatures, and when necessary sends a 12 volt signal via a low pressure cut-out switch (mounted in receiver-drier) to the compressor control circuit. The normally closed cut-out switch protects the compressor from lubricant starvation as a result of running with too low a pressure in the refrigerant system.
Operation of the a.c. compressor is controlled by the engine management ECM, which under certain conditions will override the a.c. request signal and switch
cycling off the the air conditioning. These operating conditions include: engine speeds below idle to help prevent stalling; wide open throttle to make available full
engine power; near maximum vehicle speed to increase engine cooling margins.

does this mean that if the leads are closed there is either too low pressure or something otherwise wrong with the drier?
1266172
 

·
Registered
Joined
·
3,419 Posts
If you have continuity across the switch, it is "closed" allowing current to pass to the clutch and operate the compressor. Typically in a situation where you have insufficient cooling, there is enough pressure to close the switch but as soon as you start running the compressor the switch opens because you are low on refrigerant and the pressure drops too low, opening the switch. The next step would be to hook up a set of gauges and observe the system's pressures to verify what is actually happening. If the system is actually low on refrigerant, the next steps would be to find the leak, remove the refrigerant, repair the leak, pressure test, evacuate and then recharge.
David Teitelbaum
 
1 - 17 of 17 Posts
Top