01 S80 a/c service mechanic said compressor cycling normal??

[jimmy57]

There was a CCM upgrade that altered on and off temps for compressor but i think it predates 2001 but that could be a solution.

[midimykeys]

Thanks for your help Jimmy. I'll pick up a temp sensor probe at a salvage yard and see if it might be that. I will locate the cabin filter and check to see if it's clean. I know the blower stays on for a bit as does the cabin fan intermittently after the car has been shut off to dry the evaporator.

[johnboneske]

You all do realize that an AC compressor does cycle. If your doesnt, that means the system is lower than normal on refrigerant. When operating correctly the cycle...period! Yes, I am HVAC certified!

[abscate]

Volvo put a lot of capacity into P2 a/c systems. Choosing expansion valve as control for refirgerant allowed for better idle cooling. As a result of the semi-overcapacity the system has a higher freeze risk for evaporator. Evpa temp sensing and cycling compressor to avert freezing is a normal function.
Do you turn down fan volume to reduce blower speed?
Have you checked and made sure the cabin filter is clean?

A new evap temp sensor might change it but it would be a gamble without a test to see if it is accurate. I will pull them out of case and let them sit for a few minutes and then check in VIDA to see what temp it shows and measure the temp where it is laying to see if the probe and my thermometer agree.

True dat!!! My new to me P2 gets 50 degrees F of temp delta after 15 minutes idling at 1500 rpm. I'm sure I can service it and degrade that......

[midimykeys]

If you guys say so, although my air was fairly cold before I started messing with refrigerant, and I never heard the cycling. Now after an evap and fill, every 15 seconds..."click" then 15 seconds... "click". I can hear it in the car and feel the temperature difference. I have never had a car with an air conditioner that I could feel a temperature change when the a/c was on. It takes the car about 7 minutes in 85 degree heat to get to a comfortable temp inside, and 1/2 the time I'm driving, I am where I need to be in 7 minutes. I know this is not normal. My old 2001 S60T was very cold after about 10 seconds.

[jimmy57]

OK, now that you've listed the cooling performance I do have a different opinion.
It's 94 and very humid today (it's ft worth TX, if it wasn't this humid the atmosphere would have heated this air to 101-103) and my 04 V70R was cold in 30 seconds and had the car comfortable by the time I had gone 1 1/2 miles to the highway at 35 mph. No dark tint windows or any other aids on the wagon to make its a/c cool more quickly.
You likely have an expansion valve issue. Other than evacuate and recharge the expansion is easy as it is in the firewall opening where the two a/c lines enter.

I'm diagnosing that since it has been verified with correct charge and pressures are not off so much as to be obvious to your tech.
I'd be curious of the pressures are at 1500rpm, 3/4 fan speed, recirculated air, and 8 minutes of run time (the Volvo and industry standard test conditions).
Pressure readings at idle are almost never valid. Exceptions are newer vehicles with variable displacement compressors (not this Volvo, but the ones with 3.2 6 cylinder and any P3 model in US uses this type compressor). Even the ones with VD compressors have a little presure change between idle speed and 1000 rpm.

All others have too low compressor speed andthus pumping volume for the gauge pressure readings and outlet temp values to be valid.

[webcorrecto]

Dear Friends

In my 2005 s60, I got a bad A/C hose that caused a leak, so I had it replaced about 2 months ago. A week after that the problem of evaporator freezing started during a long trip.
Same behavior, looked for solutions, and found that I had to change sensor, it is a thermistor, NTC 2.7kohm @25°C, theoritecally, if you can locate it in an electronics parts shop, you do not need to buy the OEM part. But I did not risk it and bought the new part. Installed it and worked flawlessly for about 1.5 hours. In heavy traffic. It was a dream. But it finished later when cruising. It did the same behavior. Turned off the AC with the dash button, and waited a minute, later turned on , and worked ok for a while. It was extremely variable, from 5 minutes to 1 hour, I could even hear the compressor turning on and off and the expansion valve hissing when doing so. I could tell that it was going bad, because suddenly the compressor did not cycled, and a few seconds later the air became hotter, did the same process of turning off and on the AC and worked fine again. Sometimes it did not worked, air got really cold and then hot in one minute, compressor did not cycled. Also the tubing coming from the evaporator in the engine compartment is also frozen when air got warmer, and defroze when I turned AC off.
I am thinking that maybe debris may have gone into the system when changed the hose? could this cause the problem? My temp sensor was bad, I measured it and compared to the new one, it was truly bad, but still the AC is not working completely well, because of this problem, seems intermitent, sometimes it seems to listen to the sensor, and sometimes not.
I am confused, I hoped the sensor would solve the problem, and sometimes it seems to do it.But still get the problem. Does the system has a pressostat also that may prevent the compressor from shutting down? or this sensor does all the job?
Thanks for your help and expertise.