Air Con issues

[QldKev]

I posted a few weeks ago about my aircon issue;
a quick recap. Whilst in aircon mode ALL air stops from every vent, including the windscreen.
i haven't had a chance to get the car to an aircon specialist yet.

We went to the Gold Coast for the long weekend, and it done it again - no air flow, but fan still running.
The climate control was set on 21, but the fan speed had been manually set to 3. Last time it did this I
noticed the air con lines under the bonnet frozen, so I though this air flow issue may be by the air
box freezing over, hence not allowing air to flow.

I switched off the aircon but left the fan running, within a couple of minutes airflow returned, and kept
increasing until I had full flow back. We then switched back on the air con; about 30mins later we lost flow
again. We turned the air con off, and again after a couple of mins air started coming through. This kept
happening over the trip.

It's something I think I definately have to take the car in for, but what could it be? Is there an adjuster / valve
that is supposed to prevent this from freezing.

QldKev

[Tree cutter]

There should be a temp probe that goes into the air con element in your dash. I would say that it has either fallen out from between the fins of the air con element or is not working. It should turn the a/c compressor off when it gets too cold.
Another thing to check would be the air inlet filter that is under the plastic thing that your wipers are sticking out of.If the filter is blocked it will slow down air flow through your air vents which can cause your system to ice up. The filter is on the passenger side.

[vxblowncalais]

Could also be short of gas. This will make it run colder than normal in parts of the box causing icing up and progressing through the air box.

[isittrue99]

I’ve had all sorts of problems with the climate control in my VR Calais
The vents would not open reliably, I pulled out the "vacuum box" in the dash under the radio and opened it up. Three or four of the solenoids were intermittent. The legs had huge cracks in the soldering joins. Resoldered them -works. Hard to put the vacuum hoses back on if you’ve got big hands, had to get the wife to help with that bit.
Fan/blower stopped working, replaced the transistor under the black plastic cover below the windscreen (thanks guys) with a MOSFET from Jcar-works
I have one problem left, same as you OldKev. On a long trip the internal vents stop letting air through, even when on high. If I manually turn the A/C off the air flow slowly comes back over about 10 or so minutes. If I stop the car and come back later there is a huge puddle of water. So I recon she is freezing over. I know there is one thermister (tep sensor) on the actual climate control panel on the dash. I changed this, but no joy. Im thinking it might be the ambient air sensor as this seems to read a bit high but I don’t know where to look for it. Any Ideas fellas?
Cheers

[QldKev]

I ended talking to my local air con dude. He didn't even look at the car and said that it is caused from the variable speed compressors used in cars today, and when they stuff up they always run flat out and freeze every thing up. The controller is internal to th compressor, so basically new compressor time.

I haven't been back, and am learning to live with it.

QldKev

[aceventura]

I don't think the VR or VS had variable speed compressors. Take a look at this info - it may help to diagnose an evaporator temp sensor problem.

[isittrue99]

oh bummer! I'll let ya know if I manage to get it fixed, hope I can . The ambient air tep sensor in front of the radiator is reading a bit high (about 5oC) . Im going to put a 300 or 400 ohm resistor in series with it to rase the resistance leve a bit and get a proper reading.If that works (which I doubt ) i'll be stoked. Failing that I might replace it. Also looking to find the internal evap sensor (thanks aceventura) that might be stuffed. Keep my finger crossed
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[TonyJZX]

lol new compressor

that's a good $600-$700 or so

damn it

[isittrue99]

Hi guys
Just to let you know, and thanks to everyone that has help me out with suggestions and info!
I ended up putting a 220 ohm resistor in series (in-line) with the ambient air temp sensor. It now reads 11oC when actual temp is 10.5oC and 36 when actual is 39. At temps up to about 33oC she’s spot on the actual. Not too bad an error over the range. It was reading +5oC. After that I took her for a drive with the CC on and then check the sensor outputs again. They were all in acceptable ranges. The Evap sensor value was previously 45% and now reads 55% which is about 5oC which is in the 2-12oC range. The 45 % equated to about 13-14oC outside this acceptable.
I don’t know how adjusting the ambient air sensor has affected the evap reading but it seems to be better, maybe it let more outside air in ?. The real test will be the long trip over Xmas. Let ya know if it ices over again. Fingers crossed.
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[isittrue99]

Hi Guys
FYI
The CC iced over on the way up to bundy. However, it was raining constantly they whole way and the humitidy was in the 90%! So that could be just because of that?
Anyway, we should get a much better idea on the way back.
I have also Uncovered the sun sensor on the dash and fixed the theromstat. the car never got up to correct running temp and this could affect the hot/cold air mixing.The heater works much better now
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