Volvo ACC Automatic Climate Control queries

[tofufi]

Hi folks,

I've sorned my 740 turbodiesel at the moment as it's not getting used. I'm getting it up to temperature once a month and running the AC to keep everything working.

I noticed today that the AC pump wasn't spinning - the clutch wasn't being activated

So, questions:

1) with the AC on, and the temperature dial set at minimum, should the pump always be running? Ambient temperature when I tried was probably 15-17 degrees, so perhaps it wasn't running the AC much due to the low temperature? There was no significant temperature different between the pipes

2) what controls the pump operation? Most vehicles have a temperature sensor or switch in the evaporator, but I don't think the ACC system does... (though it does have one downstream of this)

3) Since I fitted the system, the climate control has always worked well at regulating the temperature in the cold. However, when it's hot outside I always end up being blasted by cold air while the rest of the car remains feeling hot. Is this normal for 740/940s, or might I need to check the ACC interior sensor is getting a flow of air over it from the interior? (there's a vacuum tube from the engine for this purpose)

Ta,
Jim

[MiniNinjaRob]

I have ACC in my 940, the temp gauge to control it is in the headlining light pod.

If I lower the temperature on the dial it does blast cold air out a lot but if you open more vents across the dashboard that effect is lessened quite a lot. I suppose if you only drive alone most of the time you might not have opened the passenger vents.

If you have an estate it’s hard for the AC to cool the whole car down due to the amount of glass and air volume to deal with. I’ve always found estates to be slightly harder to cool than saloons of any make.

Have you got the fan speed and air direction on auto as well? I sometimes put fan speed on auto then just have windscreen vents on which is quite nice.

[Laird Scooby]

The compressor clutch isn't permanently engaged Jim, it will cycle in and out as the need arises for the system to maintain the temeperature you've set. If ambient temperature is below the set temperature, it won't bring the compressor in but if you set the direction control to the screen and the fan to high, temperature to maximum, that should bring the compressor in. It's designed to put hot, dry (conditioned) air onto the screen to defog it under these conditions.

If that doesn't bring the compressor in, check the codes - ignore 1-6-1 if it's cloudy! (think it's 1-6-1 from memory, it relates to the sunlight sensor)

From what you've said though, it doesn't sound as if there's anything wrong, just circumstances.

[tofufi]

Hi folks, thanks for the replies and apologies for the delay reply.

I went to the car today- it's a bit (!) warmer, and still no compressor kicking in.

Giving a +ve feed to the compressor made it kick in.

Bypassing the pressure switch made the compressor kick in.

Guessing I've either got a duff switch, or the gas has escaped since fitting it a year or two ago (I know where my money is!)

Guess I'll book it in for a pressure test sometime soon! (As soon as it's not SORN any more and I'm back to needing it!)

Strangely, I didn't seem to have any codes. The blue AC led went on and off in a sequence I struggled to interpret, but I think was 1-1-1... I did take a video if anyone wants to see?

[Laird Scooby]

Originally Posted by tofufi

Hi folks, thanks for the replies and apologies for the delay reply.

I went to the car today- it's a bit (!) warmer, and still no compressor kicking in.

Giving a +ve feed to the compressor made it kick in.

Bypassing the pressure switch made the compressor kick in.

Guessing I've either got a duff switch, or the gas has escaped since fitting it a year or two ago (I know where my money is!)

Guess I'll book it in for a pressure test sometime soon! (As soon as it's not SORN any more and I'm back to needing it!)

Strangely, I didn't seem to have any codes. The blue AC led went on and off in a sequence I struggled to interpret, but I think was 1-1-1... I did take a video if anyone wants to see?

Video would be good Jim, sounds like the "All good" code from what i remember though. My guess is they only just put enough gas into the system to get it running, temperature drops will cause it to contract so the ambient pressure isn't high enough to bring the compressor in. Could have a minor leak as well through lack of use.

[tofufi]

Originally Posted by Laird Scooby

Video would be good Jim, sounds like the "All good" code from what i remember though. My guess is they only just put enough gas into the system to get it running, temperature drops will cause it to contract so the ambient pressure isn't high enough to bring the compressor in. Could have a minor leak as well through lack of use.

They put the amount in that their chart said - but as my system is a bit of a hybrid (760 diesel pump, 940 under-dash components, miscellaneous pipework) we weren't totally sure how much should be in there.

Will try to upload the video!

[Laird Scooby]

Originally Posted by tofufi

They put the amount in that their chart said - but as my system is a bit of a hybrid (760 diesel pump, 940 under-dash components, miscellaneous pipework) we weren't totally sure how much should be in there.

Will try to upload the video!

After charging and proving the system works, leave the gauges connected and switch the compressor off then let the pressure on the low side stabilise. It should be about 10% above the pressure that the pressure switch operates at, usually about 30-36psi so depending on the switch, 33-40psi as a guide. However, i know on my Rover the switch is nearer 40psi (according to the gauge that came with the DIY kit i used to regas it) so i had to put a bit extra in (about 50-55psi) to make it reliable.

Most garage type places will err on the side of caution and try to keep the pressure down but often that's a false economy as could be the case with yours.

[tofufi]

+ YouTube Video

Managed it

I repeated it several times, but no change I think. This was after an ignition off cycle.

[Laird Scooby]

Originally Posted by tofufi

Managed it

I repeated it several times, but no change I think. This was after an ignition off cycle.

https://www.volvoclub.org.uk/faq/Hea...iagnosticCodes

I was right, 1-1-1 is the "all good" code. It won't show a code for low gas pressure though.