A/C Clutch problem

Astromain69 · Post by **Astromain69** » Fri May 13, 2011 4:36 am

A couple of months back, whilst travelling in the back, my better halfs little girl started to get a little scared (not my driving - honest!). She kept on saying that there was an occasional & regular heavy breathing in the rear of the van, like "Darth Vader". On investigation it was the A/C pumping air through the rear vents but at regular intervals, not all the time.

Whilst looking under the bonnet, with the A/C on I noticed that the A/C compressor starts and stops (spins) at regular intervals (every x seconds precisely). And of course, this is causing the air being pumped into the rear of the van.

Reading the Haynes manual last night it said that the control module will operate the compressor clutch depending on the revs / throttle position, so I'm thinking this could be the problem.

Has any experienced this before? If so did you manage to fix it?

Thanks in advance

Craig

astroturf · Post by **astroturf** » Fri May 13, 2011 3:45 pm

Not quite sure what you are asking.

Best bet would be to determine the operating pressures of the AC System.

Keep us posted, Jim

Astromain69 · Post by **Astromain69** » Sat May 14, 2011 2:13 am

Hi Jim,

I suppose my first question is - when the A/C is switched on should the compressor spin continuously or start & stop at regular intervals?

If it should continuously spin, as mine is starting & stopping at regular intervals is it the control module that is engaging and releasing the compressor clutch? If so what would cause this? And how can it be fixed?

Thanks

Craig

astroturf · Post by **astroturf** » Sat May 14, 2011 5:19 am

Craig,

Let's start here:

http://www.familycar.com/ac1.htm

Jim

PS If your AC System has not been serviced in the last Three Years, It may be time to take it to an Automotive AC Specialist.

PSS Read the above Link and come back with any questions. I will do my best to help you.

LiftedAWDAstro · Post by **LiftedAWDAstro** » Sat May 14, 2011 9:39 am

If the temp inside the van is satisfied, the A/C clutch will cycle. If you place the temp on the coldest setting and the fan on highest speed, does the clutch stay engaged? If it doesn't you are probably low on refrigerant.

Astromain69 · Post by **Astromain69** » Sat May 14, 2011 10:12 am

Hi Jim,

Thanks for getting back to me and the link. I will read the info and get back to you with any questions.

Rgds

Craig

Astromain69 · Post by **Astromain69** » Sat May 14, 2011 10:15 am

LiftedAWDAstro,

Thanks for the suggestion, I will test the A/C as described and will get the gas checked too.

Rgds

Craig

doyoulikeithere · Post by **doyoulikeithere** » Sat May 14, 2011 11:02 am

I'm confused.
I always thought the compressor had absolutely nothing to do with the airflow out of the vents in the rear of the van.
I understand that the compressor is part of the cooling system, but I thought that it pumps freon (or whatsitcalled) inside a closed system.
Compressors always cycle on/off. Electric fans pump the cold air around inside the van. Are they wired together somehow?
Maybe I misunderstood...

Quill · Post by **Quill** » Sat May 14, 2011 12:02 pm

I am not sure on this, but I am not sure it's the clutch. Sounds more like an electrical problem.

LiftedAWDAstro · Post by **LiftedAWDAstro** » Sun May 15, 2011 9:46 am

I took it as the refrigerant is what is making the noise and not actually the blower fan. Lets see what the test tells.

astroturf · Post by **astroturf** » Sun May 15, 2011 10:46 am

The rear ac unit is where Darth Vader lives.

You see the rear ac has an expansion valve. So when the compressor cycles off, the flow of refrigerant passing thru the rear lines gives off a sound... That sound can only be heard by a Good Set of Ears.

As far as Darth goes... He comes from a good imagination.

LOLz, Jim

doyoulikeithere · Post by **doyoulikeithere** » Sun May 15, 2011 11:58 am

Ahhhhh, I see.
Thanks for the expl.
May the force be with you.

Astromain69 · Post by **Astromain69** » Sun May 15, 2011 12:43 pm

I ran the test and here's what I found.

With the temp setting as low as it can go. The switch for the rear A/C does not engage the compressor at all.

I then turned on the cab A/C with the switch and the compressor engaged. It is on for 3 seconds and off for 7 seconds, this repeats precisely at those times. Also just before the compressor turns on / off I hear a 'click' under the bonnet which I assume is a relay but could be wrong. I'm not exactly sure where the noise is coming from but it is around the accumulator (receiver dryer identifed on the diagram provided by Jim's link above).

Next step is to get the system re-gassed.

Thanks for all your responses.

Cheers

Craig

astroturf · Post by **astroturf** » Sun May 15, 2011 2:56 pm

Craig,

Thanks for the update.

The Rear Ac Control only turns the rear blower on/off. The Ac System/Compressor is controlled from the Front Control.

It sounds like you are on the right track.

Good Luck, Jim

Astromain69 · Post by **Astromain69** » Mon May 16, 2011 12:34 am

Thanks Jim, will keep you informed.

Rgds

Craig

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