Hi,

Short version:

A/C clutch only engages when I start the engine (even with A/C switch set to off) but kicks off in a few seconds. Can force it on by overriding the relay with a paper clip.
Gap between clutch plate and clutch body: a tight 0.63mm.
Fresh refrigerant, pressure OK.

So far I tried:
- using a neighboring identical relay (from front AND rear window washer?) - no improvement.
- reducing the gap to a tight 0.5, 0.4 and 0.3mm using steel zip ties and bread clips - no improvement.
- tapping on the clutch plate with a stick (engine and A/C on) to force it to close and kick in - heard the clack between two parts but clutch did not engage.


Slightly longer version:
Last month I recharged the freon in my Volvo XC90 2003 T6 because the AC was getting weaker.
I paid a little bit more than usual (~180$) for it because the service included a free freon recharge if there is a leak / other problem with the AC system if I'm doing all the repairs at this shop.

I drove the car for a week until the AC started to act funny, blowing hot air at times until it died completely.
I returned to the shop, they used a black light to check for leaks and didn't find any, checked the pressure too and said that it was full. Their mechanic said that the compressor unit isn't engaging at all. We checked the relay and it was fine (I used the washer relay from nearby slot which is identical).
After scratching his head for a while, the mechanic removed the relay and stuck a bobby pin in there, completing the circuit. The AC engaged and started to blow cold air again.

The clutch does engage when I start the vehicle regardless on whether the AC is on or off(and blows cold air in the cabin), but kicks off in a couple of seconds.
Measured the gap between the clutch plate and clutch body, it was a little over 0.63mm.

Now the interesting part:
Seeing his "success", another sketchy looking mechano (the boss?) came out and started speaking Italian to the first one, presumably asking about the progress. After receiving the response, he told me that the problem is unknown and that they must take the car for the thorough inspection. He said that it would cost me 50$ to read the codes (even though I had my codes read for free in any other location!) and if they are unable to find the easy solution through the codes, they would need to spend several hours on the car's electrical system (69,99/hr) + the labor. I'm 24, but I look even younger, so I wouldn't be surprised if they tried to rip me off...

I forgot to mention that in the process both mechanics used a multimeter(?) to check for the connection between each of the holes and random bolts near the engine. One of the holes did not light the lamp on their tool and they seemed mildly concerned about it, although they did not point it out as a problem.


I tried to fix the gap by jamming stainless steel zip ties (plastic ones are too thick) through each side of the ring spring in such way that zip tie passes under the rubber thingy *see pictures below**. Managed to reduce the gap to a tight 0.4 and 0.5mm by moving the ties a little and later on, to a tight 0.3mm by adding bread clips. Neither setup made it blow cold air again.

Frustrated, I even tried to tap (very firmly and convincingly with the engine running and A/C button on) on the clutch plate with a wooden stick to make the gap close and force the compressor to work but, surprisingly, it didn't. I also observed that the clutch plate becomes harder and harder to turn manually as I add extra zip ties, even though the gap was nowhere close to 0.3mm. Not that it was spinning freely without them but...

Anyway, as before, the only way to engage the clutch is by starting the vehicle (runs for 5-10s) or by overriding the relay with a paper clip.

Pictures: XC90 A/C Shimming attempt (didn't work) - Album on Imgur

Am I doing something wrong or is this solution just not for everyone?
Is it risky to simply jam in a paper clip when I really need A/C? Is the circuit still protected by a fuse?

So my question is:
I there anything else I can do myself to try to fix (or at least troubleshoot) this problem as I would like to avoid any further services from this place, because I feel like I'm forced to fix the problem at their shop if I want to keep my free freon recharge?

Thanks in advance,
Dmitriy

P.S The A/C unit is very very very hard to access so removing it would be the last thing I will attempt... if even...

 

Their explanation and expectations sound reasonable to me. However, if the relay is pulling in on initial startup, I think you do not have an electrical problem, so I don't think it'll require finding a bad wire. Rather, I think it is a logic problem and their approach to it is correct.

 

You need to find out if there is power to the clutch when it cuts out. If there is, it's the clutch. If there isn't, and the relay is good, then the car is shutting the AC off and codes will be needed. Hopefully their scanner can communicate with the CCM. A lot of indy shops can't.

 

Hi and thank you for your reply.
The thing that I'm worried about is that they will call me and say something like "ok, we worked on your car for 7 hours now and found the problem. Please pay for the work already done before we proceed"... I hate being a hostage of the situation.

 

Thank you for the reply!
I will attempt to check the connector that goes to the compressor's magneto for the connection. It's a very tight fit, but I will try. But if checking for power involves having the engine running (or even the keys inserted) I will not risk my limbs.
Someone also suggested to check the evaporator sensor and I think it's located under the dashboard next to driver's seat. Are those universal? Can I just take one from another vehicle and jam it in?

 

The engine does need to be running, so don't risk what you are not comfortable with. The evap temp sensor could be the problem, but you would need a scanner capable of communicating with the CCM and seeing data. I think this might be beyond what this shop can diagnose. I would recommend a dealer or a shop that specializes in Volvo.

 

I've located the power pin that goes to the magneto. It's fairly accessible ( in a safe way) using long jaw pliers. It's a one wire pin (+?) so I guess the negative goes through the compressor body(?). Can I use this to my advantage?

 

Yes, just one wire. The connector is clipped to the compressor. If it has power, the car is commanding the AC on.

 

Okay, silly question, but how do I check for the power in 1 wire case?

 

What are you using to test? Voltmeter? Test light?

 

Multimeter
Looks almost exactly as shown here Mastercraft Digital 5-Function Multimeter | Canadian Tire

 

Set to DCV. Probe one lead into that connector (preferably with it connected if you can do so without damage). Clip the other to any ground. Should have battery voltage with AC on.

 

That's pretty much how I imagined it, just wanted to make sure I don't do any damage to the component or self because I hesitated to ask.

I will have my codes read (hopefully) in about an hour, I will ask them to check if the connector/clutch is being sent power.

 

I had my CCM codes read!

CCM-001F air quality sensor: Signal too high
CCM-0020 air quality sensor: Signal too low
CCM-0004 compressor: Faulty signal

Screen picture here: CCM codes XC90 2003 - Album on Imgur

Where are these sensors located?

 

Its located in the air box where the recirc draws air in (passenger side under the cowl). Those shouldn't cause it to shut off though. Did they clear the codes?

 

Yes, they cleared the codes.

 

Is the problem still present? I would have to look into that compressor code when I get a chance

 

Yes, the problem is still present. I just performed a thorough verification using different manual and auto modes on the climate control panel. Compressor sits dead silent.

As I understand it, this is just the resulting message from the compressor receiving a faulty signal from the sensor.

 

The compressor doesn't receive a signal from any sensor.

 

The original AQS costs over 300 CAD, but a friendly seller from China has an identical one(?) for VW for 13$. I've read that some XC70 and XC90 owners used these sensors on their vehicles and it worked!
Source: CCM-001f code fixed on the cheap, AQS now working again.