A/C Problem

[gkm]

Hey all,

I'm hoping you all can provide me with some sage advice. My Bobcat CT335 is giving me fits w/ the a/c. I had the compressor replaced under warranty and I'm still having issues. The freon charge is fine (I think) as it's around 35 psi on low side when running. The compressor short cycles on and off (a/c light on switch also blinks on/off). I cleaned the condenser well and checked the four vent filters and they are clean. The belt adjustment is fine; however, when compressor "catches" it sometimes will squeal like a stuck pig! I'm wondering if the new compressor clutch is bad?

Any/all advice would be greatly appreciated.

Thanks in advance for any help.

Greg

 

[RickB]

Overcharged? What is the high side pressure?

 

[gkm]

Overcharged? What is the high side pressure?

Thanks very much for the reply!

Should I check high side running or not? What should high side pressure be? Also, what is proper low side pressure w/ tractor running?

I forgot to add that the A/C "works" when it wants and then quits on its own. Seems really odd to me, but then again, I'm not experienced w/ a/c other than checking pressure and charging.

Thanks again,

Greg

 

[Stimw]

When it quits is the evaporator freezing up? (covered with snow)
A lot of AC systems need to be slightly over charged. The perfect charge will ice up the evaporator.
If the system has a sight glass check to see if there are bubbles. That indicates low refrigerant.

 

[jaotguy]

did they top off the oil when they changed out the compressor ?

 

[gkm]

When it quits is the evaporator freezing up? (covered with snow)
A lot of AC systems need to be slightly over charged. The perfect charge will ice up the evaporator.
If the system has a sight glass check to see if there are bubbles. That indicates low refrigerant.

Thanks, but no, the evaporator isn't covered w/ frost. I cannot find a sight glass, but will have to look w/ mirror. It is a new compressor and asked the dealer if it was filled w/ oil and they told me it was.

 

[RickB]

When it quits is the evaporator freezing up? (covered with snow)
A lot of AC systems need to be slightly over charged. The perfect charge will ice up the evaporator.
If the system has a sight glass check to see if there are bubbles. That indicates low refrigerant.

Bubbles present in the sight glass are not an indication of an undercharged R-134 system. A properly charged system will have the proper amount of refrigerant, not more. Operating pressure specs vary by application AND ambient temperature. 35 lbs on the low side while running seems high to me, but I have no direct information on the charge quantity or operating pressures of this particular system.

 

[MyJoBota]

You will need both highside and lowside pressures as well as ambient temp. to accurately diagnose. Why was the compressor replaced (catastrophic failure) and is that the only part replaced?

 

[Loadstar]

If you check pressures not running all that tells you is there is refrigerant in the system. Check it running and check it near design rpm (unless you have electric fans). Your probably going to have to sit down with a meter and figure out what is dropping compressor out like that. As for the refrigerant side... If it were me I would blow it off, pull a good vacuum. and weigh in the correct charge so you absolutely know it's correct.

 

[gkm]

You will need both highside and lowside pressures as well as ambient temp. to accurately diagnose. Why was the compressor replaced (catastrophic failure) and is that the only part replaced?

The bearings were shot...squealed all the time.

Do you know what the high/low side pressures should be? Ambient temp is around 70 deg. right now during the day. What should I expect for a pressure differential between high/low side?

Thanks in advance.

 

[gkm]

If you check pressures not running all that tells you is there is refrigerant in the system. Check it running and check it near design rpm (unless you have electric fans). Your probably going to have to sit down with a meter and figure out what is dropping compressor out like that. As for the refrigerant side... If it were me I would blow it off, pull a good vacuum. and weigh in the correct charge so you absolutely know it's correct.

Thanks...I cleaned it really well yesterday and it was dirty, so that shouldn't be an issue now. It seems to me that the clutch may be an issue as it appears to be locking up. I'm trying to get the dealer to provide me w/ HVAC troubleshooting and schematic information so I can try to figure this **** thing out.

 

[Loadstar]

Thanks...I cleaned it really well yesterday and it was dirty, so that shouldn't be an issue now. It seems to me that the clutch may be an issue as it appears to be locking up. I'm trying to get the dealer to provide me w/ HVAC troubleshooting and schematic information so I can try to figure this **** thing out.

I didn't say to clean anything. What do you mean your clutch is locking up?

 

[gkm]

I searched lots of threads yesterday, but for some reason, I didn't come across this on:http://www.tractorbynet.com/forums/kubota-owning-operating/176647-what-time-c-fail-7.html. Lots of good info and I'm on my way to troubleshoot.

 

[MyJoBota]

sounds like to me your system is either over charged or you have a restriction in the system causing excessive high side pressure hence the belt squeel. You need a gauge set hooked to this system to accurately diagnose. If I had to guess I would say the old compressor failed internally leaving a contaminated system behind causing a restriction.