2002 S60 AC blows cool air for a while (between 20-60 min) then stops blowing

coded9 · Post by **coded9** » 07 Jul 2016, 20:36

I'm having issues with my ac. Whenever I run the AC it will blow cool air normally for a while ( lowest around 20 min, usually messes up no longer than an hour). if i turn the AC onto max at this point it makes a wheezing sound but it doesn't actually blow anything at that point. you can still feel cold air coming out of the vent, only if you put your hand on it.

I read somewhere else about a similar problem with a different make and the issue being related to the ac clutch, but i'm only not sure just because it's not that i stop getting cold air entirely, somethings got to be overheating i think anyway. the climate control panel is warm at this point as well if it helps any? However it does work normally again after at least 30 min.

Post by **oragex** » 07 Jul 2016, 20:42

Open the hood, are the a/c lines covered in white ice?

FCPEURO · Post by **FCPEURO** » 08 Jul 2016, 11:25

Hi Coded9,

The issue could possibly be a faulty Blower motor Resistor.
You can find it on our site here: https://www.fcpeuro.com/products/volvo- ... 90-8693262

This is located at the blower motor and control the speed of the blower.

If you have any additional questions please feel free to ask, we're always happy to help.

Thanks

Jason

Post by **chrism** » 08 Jul 2016, 14:40

If it blows good and cold for the 20-60 minutes and then starts to restrict airflow out of the vents, then it sounds like the evaporator temp sensor is not functioning properly and the evaporator is freezing up. What happens is the sensor doesn't tell the compressor to cycle off so the compressor runs and runs and runs until the evaporator coils freeze over and restrict the airflow. The more humid your climate, the sooner it freezes up.

Test: Next time you're running the A/C and it starts to suffer restricted airflow, let the blower continue to run but click the A/C button OFF (which shuts the compressor off). If the airflow slowly restores after a couple minutes then it's a good bet that the evaporator was freezing up.

The sensor is located in the side of the evaporator box just above the gas pedal (LHD cars) - I believe you have to drop the panel above the drivers feet to gain access.

When my evap sensor failed I pulled it out and got the following temp vs resistance readings:

Garage Temp (80 deg?) = 1400 ohms
77 deg = 1500 ohms
65 deg = 1700 ohms
43 deg = 2200 ohms
Freezer Temp (28 deg?) = 2200 ohms

Jimmy57 that frequents this forum told me that a healthy sensor will read approximately 10K ohms +/- 200 at freezing and 3k ohms at 25C/77F. So obviously mine was way out of whack. Sure enough, a new sensor fixed it. $35 and 10 minutes under the dash.

coded9 · Post by **coded9** » 08 Jul 2016, 15:05

I took a drive today to get some errands done hoping it would replicate the issue,but i don't think it's been on long enough (probably 20 min at the most without a break, i also had the temperature at 72 instead of 70 so that might have prolonged it a bit). I checked that hose, it wasn't frozen but no shortage of condensation either.

I'll have a good chance to try your test while a got a long trip in a few days. I'll mention how it goes, thankfully doesn't seem too hard from that video you shared. good chance to test out the new multi meter!

Also Jason, that was the second thing i thought of (first being blower motor). It would make plenty of sense if that turns out to be the case.

Post by **oragex** » 08 Jul 2016, 20:50

Don't forget to check the cabin air filter in the process

coded9 · Post by **coded9** » 12 Jul 2016, 18:27

chrism wrote:If it blows good and cold for the 20-60 minutes and then starts to restrict airflow out of the vents, then it sounds like the evaporator temp sensor is not functioning properly and the evaporator is freezing up. What happens is the sensor doesn't tell the compressor to cycle off so the compressor runs and runs and runs until the evaporator coils freeze over and restrict the airflow. The more humid your climate, the sooner it freezes up.

Test: Next time you're running the A/C and it starts to suffer restricted airflow, let the blower continue to run but click the A/C button OFF (which shuts the compressor off). If the airflow slowly restores after a couple minutes then it's a good bet that the evaporator was freezing up.

The sensor is located in the side of the evaporator box just above the gas pedal (LHD cars) - I believe you have to drop the panel above the drivers feet to gain access.

When my evap sensor failed I pulled it out and got the following temp vs resistance readings:

Garage Temp (80 deg?) = 1400 ohms
77 deg = 1500 ohms
65 deg = 1700 ohms
43 deg = 2200 ohms
Freezer Temp (28 deg?) = 2200 ohms

Jimmy57 that frequents this forum told me that a healthy sensor will read approximately 10K ohms +/- 200 at freezing and 3k ohms at 25C/77F. So obviously mine was way out of whack. Sure enough, a new sensor fixed it. $35 and 10 minutes under the dash.

i'm almost ready to say it's probably evaporator sensor. It seems that when the ac does start "seizing up" if I leave the ac off (fans on) for at least 10 minutes or so, it returns to normal flow when i switch it back on, it does take a minute or so for the fans to run normal when switching back and forth (i tried all this on medium blower setting to keep the difference noticeable). I did try checking the resistance, the readings weren't quite as low as yours (i think i got almost what it should be. like in the 2.5-.7 range at ) I did check it again a couple minutes ago, it's at 450 ohms at 90 degrees (maybe higher). i know measuring it after a bit inside (at around 74).

Also i did check my cabin filter, still relatively clean (replaced last year, probably going to order it with the sensor).

Post by **chrism** » 12 Jul 2016, 21:35

When you're running the AC for a while, does the compressor run steady without cycling, or does it cycle on/off every minute or so as it should?

coded9 · Post by **coded9** » 13 Jul 2016, 03:05

chrism wrote:When you're running the AC for a while, does the compressor run steady without cycling, or does it cycle on/off every minute or so as it should?

How can I tell if it is cycling or not?
When it cycles shouldn't it make a hissing sound or something like that? I'm a bit unsure what I should've been looking for. Though if it should no it doesn't.

But now that I think of it though, I can say it will keep blowing ice cold until it seizes up, generally I have it on 70-74. It doesn't seem to really quit until that point, at least from what I can tell anyway.

Post by **hansenjg** » 13 Jul 2016, 07:01

This sounds to me like a classic case of clutch wear, needing the famous "bread clip" or "zip tie" fix. I have done this repair 3 times for exactly the kind of symptoms you discuss. The clutch plate wears, so when it engages, the spring is pulled harder. The electromagnet gets hot during operation and therefore loses some of its power, the the springs pull the clutch off the compressor. When it cools down a little, it re-engages. The bread clips or zip ties act as shims pushing the clutch a little closer to the compressor, compensating for the wear, and making the electromagnet more likely to overcome the spring tension. Simple fix. Even if this doesn't fix your problem, it won't hurt, as your car is at the age where the clutch is clearly worn. I don't have a link to it but search this forum for A/C Bread Clip fix and you'll find it. Good Luck!