Air-con blowing hot after a while

[miker75]

Hey, just wondering if these symptoms spark an idea from anyone...

During Winter, cooler months, the air-con will work perfectly... warms up and cools down without a problem.

During warmer months, same thing.. works fine...

But take today for example...took the car out a few times (30 degrees C outside.. pretty hot for here), and the air-con works fine...

However, when the car sat idle for a while (with the engine running and air-con on), the air stopped being cold and became a neutral temperature (I guess you could say it was slightly warm). Drove the car a little, same thing, so turned the air-con off.

Left the car for about an hour and a half, got back in and drove off... turned on the air-con and it was back to cold again...

I'm just wondering if there's a thermal switch or something that's failing when it gets too hot and needs to cool down? (no idea how the air-con works obviously!)

Any help would be good!

Michael

[Jedlee]

There is a heater shut off valve controlled by vacuum just below the heater core in front of the console in driver's footwell. Check that the rod is pushing the button in to shut of the hot coolant. Very easy one to check first up.

[hako]

Statesman has climate control unlike Executive and poorer relations so heater advice above will not apply.

I'd do a search on this forum unless someone else with climate control can help.

[Gus The Snail]

the ac pump on the motor is turning slower at idle as compared to that when driving , so the gas isnt flowing as quick creating the pressure needed.

you'll find if your sitting there , holding revs @ 1500 rpm , the ac will remain cool as the pump is actually able to build pressure.

[bezza]

try the tx valve

[vsv8berlinawag]

I had a very similar issue and not being an a/c expert, I went to the "professionals" and paid around $300 for a new tx valve, regas and receiver dryer. All seemed good for a while but when the next heat spell came it did the same thing. Went back and they said its the a/c clutch and for around another $250 bucks we can fix it ! Anyway to cut a long story short, I put the car on ramps and checked out the belts and found the a/c belt was like an old piece of beef jerky. It was shiny as and hard like a rock and I suspect has been on the car since new (1996) and no doubt over the years would have been slipping over the pulley to get like this especially under load i.e. when its damn hot. $7 later and the a/c now works like a new one. To think I put up with this for quite a few summers. Good luck

[miker75]

Just an update to what happens...

Was sitting in a car park waiting for my wife to come out of a store, and the A/C started blowing warm, which it tends to do on hot days after the car has been idle (running) for a while...
She got back shortly after so I drove off... and the A/C started blowing cold again...

It usually takes about 10-15 minutes for it to start blowing warm when idle..

Thanks for the input about the belts... that's at least something I can check..

[hako]

Just read your post again and one thing which hasn't been mentioned is whether the electric aircon fan (in front of the rad) is coming on when you turn the A/C on. If it isn't, the A/C will cool for a little while until gas pressures rise inside the unit high enough to operate the high pressure cutoff switch which turns the compressor off till it cools down again.
Think about it this way: the A/C is a heat pump...it removes heat from inside the car and pumps it out via the condenser in front of the radiator. During normal driving, sufficient air passes thru the condenser to remove this heat, but once the vehicle stops and idles, the only air passing thru to cool the condenser is that from the mechanical cooling fan - which is minimal as the engine is idling.
So, to overcome this deficiency, an extra electric cooling fan is placed in front of the condenser and wired so that when the A/C is switch on this electric fan will also come on.
So that is one thing I would check - turn the A/C on and the electric fan MUST come on.

[JazzyJezza77]

my air con was pretty bad firstly the a/c fan at the front of car was't turning on until i gave it a hit (so its on the way out but its been good since) now the other think and it sounds like this might be it even though the heater is turned off i.e getting good vacume to the tap and the tap moving the heater is still flowing hot water through the dash caused by the flap rusted away that stops the coolant. so effectively your air con is working but so is your heater, in theory it should get hotter the longer you run the engine and will be hotter again at idle due to reduced air speed over the condenser but i would also check the ac fan at the front if its not going check the voltage at the conector to it. a way to check if the heater is on check if the pipes are hot that are exposed d/s/f near the center console good luck.