AC compressor cycling every 7 secs but still cold

[burnout8488]

I just hooked my pressure gauge to the low-pressure port and made an interesting observation:

1. With AC button ON and Fan Speed at Low (@1/4 of the slide button): the AC Clutch cycles, and the pressure fluctuates between 22-35 psi. When the pressure is below 25 psi, the AC Clutch cuts off, and the cycles repeats itself.

2. With AC button ON and Fan Speed at High (@3/4 ---> Max of the slide button): the pressure hold steady at 32 psi, which is above the cut-out point and the AC compressor runs continuously.

My theory is when the Fan Speed is on 3/4 ---> Max, there is more heat removed the Evaporator, therefore more evaporation from liquid to gas states (simple Physics 101). Therefore more gas reaches the low-pressure side ---> keeping the pressure steady on the low-pressure side.

So if you don't want the AC to cycle, turn the Fan Speed up a bit.

Also, remember that if it is warmer outside, the compressor probably won't cycle even if you have your fan on the slowest speed. Hotter ambient temp = higher refrigerant pressure.

[JimBee]

If you do the clutch repair—which will cost you next to nothing—you'll know that isn't causing the problem. Suggestion: the easiest clutch repair is the "bread clip" shim repair. Trouble is they tend to fly out and you have to do it again, and again.

Do a search on this site for the thin wire fix. That will take a little longer, maybe 15 - 20 minutes. That won't fly out. You'll need a medium length screwdriver, a credit card, duckbill pliers and some thin wire. 22 gauge worked for me. I started with 18, tried thinner and thinner til I got to 22.

[jblackburn]

I just hooked my pressure gauge to the low-pressure port and made an interesting observation:

1. With AC button ON and Fan Speed at Low (@1/4 of the slide button): the AC Clutch cycles, and the pressure fluctuates between 22-35 psi. When the pressure is below 25 psi, the AC Clutch cuts off, and the cycles repeats itself.

2. With AC button ON and Fan Speed at High (@3/4 ---> Max of the slide button): the pressure hold steady at 32 psi, which is above the cut-out point and the AC compressor runs continuously.

My theory is when the Fan Speed is on 3/4 ---> Max, there is more heat removed the Evaporator, therefore more evaporation from liquid to gas states (simple Physics 101). Therefore more gas reaches the low-pressure side ---> keeping the pressure steady on the low-pressure side.

So if you don't want the AC to cycle, turn the Fan Speed up a bit.

Right...you're supposed to check the pressure with AC on max and recirculate to begin with.

Yes, it normally cycles on a low setting. Unless your car has a variable displacement compressor like newer cars.

Also, remember that if it is warmer outside, the compressor probably won't cycle even if you have your fan on the slowest speed. Hotter ambient temp = higher refrigerant pressure.

Exactly.

[cn90]

This is an old thread from 2011, but I have had 2 P80 (98 V70, 98 S70) and 4 different P2 cars over the years (04 V70, 05 XC90, 06 S60 and 07 S60)...these P2 cars do the same: AC compressor cycles a few times/minutes.

This is probably the reason over time, the clutch wears down, creating excessive gap, thus the need to modify the clutch.

If anyone knows the solution to avoid frequent cycling of the AC compressor (P80, or P2 or whatever model), please post...

[MoVolvos]

This is an old thread from 2011, but I have had 2 P80 (98 V70, 98 S70) and 4 different P2 cars over the years (04 V70, 05 XC90, 06 S60 and 07 S60)...these P2 cars do the same: AC compressor cycles a few times/minutes.

This is probably the reason over time, the clutch wears down, creating excessive gap, thus the need to modify the clutch.

If anyone knows the solution to avoid frequent cycling of the AC compressor (P80, or P2 or whatever model), please post...

.
Short cycling for any AC compressor is usually a sign of low refrigerant. Can also check the clutch gap.

Connect a set of gauges and refer to a Pressure Temp / Enthalpy Chart.

https://garagefixtankerchiktw.z21.web.c ... r134a.html
.

[cn90]

We already discussed this short cycling of AC in P80, P2 forums for yrs.

No one ever came up with any proven solution yet.

[abscate]

There’s no solution if there is no problem.

The P80 compressor will cycle in hot but not oppressive climates by design.

The clutch failure is when the compressor goes off and does not turn back on. If you wait 10 minutes , the magnet will cool enough that it will come back on again. That’s the one fixed with wires , bread clips, zip ties etc in the clutch face