My AC has taken to working when you start the car and sometime after that switching OFF then after a few minutes switching back ON. This started last year in the fall.
It is the fan that stops and the cold air turns to ambient air temperature. I do not think the temperature slowly lowers, I think it basically just stops blowing cold air and it is hard to feel the temperature of the air coming out the vent.
Sometimes the fan stops for less than a second and then carries on normally until it stops completely.
There does not seem to be any fixed time after which it restarts. Turning the dials and thumbwheels does not trigger any action.
I cannot find a solution or a similar question on here before.
When it is ON you can select the fan speed and the temperature to both sides.
I took the PCB (board) off the back of the control panel and filed away the PCB so that it fits into the notch without interference.
I did not add epoxy glue to hold the PCB board to the control panel figuring that the contacts fitted nice and tight.
I cannot say that the AC compressor stops or not, as it happens when I am on the highway and stopping is often a bit of a problem, also it may just start up again but I'll try to do it sometime.

When it stops working the interior of the car heats up pretty quickly and having my centre dash apart there are no window buttons fitted at the moment, the temperature this afternoon read 87° on the dash.

Anyone out there with an idea? Does the temperature sensor on the lower grille have anything to do with the AC?
This is just the third time I have driven the car this year and it happened every time, I kept forgetting that there was a whole gang of experts I could ask.
I know next to nothing about the AC system.

 

Dave, the first thing I would do, is change the fan resistor. I had one go bad on my A/C and I thought it was the head (a few years ago). The ebay substitution ones are pretty inexpensive and work fine. If it is new, and available for a low price, try it (don't know how much they are in Canada). Hope it works for you!


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I have a spare one in my spares collection, it may be worth the try. Thanks.

 

It has been proven the answer is 'no'.

Now, aside from issues with the climate control panel in the console, there are some things to consider.

First, the design of the climate control is such that if you turn the fan off, the A/C clutch disengages. This is because, if you keep the pump running with no air flow over the evaporator, system pressures will go out of range, the A/C is designed to MOVE HEAT, and if there is no air flow over either the evaporator or condenser, then no heat can be moved. So, if the climate control 'thinks' you turned the fan off, it will disengage the clutch for the A/C pump. Can a bad fan resistor cause this? I do not think so, the climate control outputs a .5 to 8 volt signal to the 'fan resistor' which the 'resistor' turns into a pulse-width-modulated 12 volt feed to the fan motor. THere is no "going backward" with any information on the status of the fan for the climate control to go on. So, a bad fan resistor cannot cause the clutch to disengage.

Well, maybe. There is a sensor (two acutely) on the evaporator that tell the controller what the temperature of the air is passing the evaporator. Perhaps the climate control will lock out if it does not like the temperature reading it is getting - due to the fan stopping. Replace the fan resistor - it's cheap and easy.



There are some other things that can disengage the clutch. The "A/C heater control module" directly connects to the clutch, but the module commands the clutch to engage and disengage based on 'permission' of the ECU.

When the climate control tells the clutch to engage, it first tells the ECU it is going to do so. The ECU responds with "go ahead" and also opens the throttle a bit to compensate for the added load.
The ECU will refuse to allow the A/C clutch to engage in a few scenarios:

1) The ECU senses a high engine temperature (the gauge should show this).
2) The ECU senses that the driver is asking for a lot of horsepower (like passing, etc; the ECU will disengage the A/C clutch to provide more HP for acceleration).
3) The ECU has detected some sort of issue with the engine cooling fan. (The little "radiator" or "low coolant" light should be on, but I"m not convinced that ALL such errors light the light.)

Just keep in mind that issues with the car OTHER than the A/C can stop the A/C from working!

As to the A/C itself, you may have a defect in the climate control circuit boards themselves (which you have obviously suspected, based on your post above). Also, there is at least one pressure sensor in the refridgerant system that will stop clutch engagement if the pressure is not what the climate control module wants to see. THis could be a bad sensor, a bad climate control circuit board part - or actually bad pressure.

 

Thanks for the comprehensive answer, I’ll have to digest it.
I had the car out today and it did not happen once. 🙄

What did happen while I was out was that the tire light came on, I checked all the pressures beside the road and all where around 40 psi. They were pretty warm, when cold I set them at 37 to 38 all around. My tires do not let much air out all summer. So next job is to fix the TPMS wiring in the dome light, it’s not a dome but what the hell.

Yesterday I had to stop fast for some idiot pulling out in front of me when a long semi was parked on the soft shoulder, he stopped dead just in time. Looking back my biggest danger was someone behind me not seeing why I had to brake so suddenly, they could only see the semi trailer which hid the idiots car.

 

As I said yesterday the AC did not stop once yesterday, was it becauseI was lucky or was it because the temperature was 10 deg. cooler?
I will have to keep track of the conditions.
The fan works at all speeds and is not erratic at all, it just suddenly stops and then after awhile restarts at the set speed.