AC Help!

[LDO]

My 85 C10 has a 305/700R4. The previous owner had the AC converted to R134. It cools pretty good but the compressor cycles off and on pretty regularly and the belt flaps a little even though it appears tight when I check it.

Is there a fix for this? No idea how the conversion was done or if done correctly. I suspected the freon level might be low but when I put guages on it to verify, it reads a little high when the compressor runs then drops off when it cycles off (a normal indication I would imagine).

Anyone have a fix for the compressor cycling?

 

[yevgenievich]

Low pressure switch might need to be adjusted. Should not cycle off untill about 18-20psi. Belt tension sometimes hard to get correct on v belt setup.

 

[LDO]

how do i adjust the LPS?

 

[chengny]

how do i adjust the LPS?

Not sure how frequently you mean when you say:

but the compressor cycles off and on pretty regularly

It would not be considered abnormal if (with the cab cooled down) the compressor kicked in for say 10-15 seconds and then kicked out for a similar length of time.

If you want to try, the cut-in point can be adjusted with the screw highlighted in the image below. Unfortunately, I don't remember which direction raises/lowers it. The factory cut-in/cut-out points for that low side switch are about 46/25 psi. And, just as info, 134a conversion shouldn't require a change in those settings.

You must be registered for see images attach

Before changing the set point, try adding some gas - just a little bit at a time - and see if that alleviates the short cycling condition.

Check for a restricted orifice tube by the presence of frost on the tubing immediately downstream of the tube's location:

You must be registered for see images attach

 

[LDO]

It would run for about 3-5 seconds, then cut for about 3-5 seconds.

I added some freon using one of those AC Pro cans with a gauge. I stopped because when I let go of the trigger and the compressor ran, it put me close to the red line.

I drove to the NAPA to get a vent temp gauge and it never got below 60F. When I pulled into the driveway at home, the compressor was running the entire time; AC on max, blower on hi setting. I didn't notice any frost on the tube but I will try checking all this again later this week. Wife & kids want me to take it easy for father's day!

 

[yevgenievich]

Need to put hi and low pressure guages on it to verify

 

[HotRodPC]

Any of you AC knowing guys that want to do a real good write up How To thread, in good detail with some pics and such, we could sure use it here on GMSB. Actually could be 3 different threads. #1 Recharging or adding Freon, #2 Conversion to R134A, and #3 AC Troubleshooting. Anyone willing to take the time to do it, I'll make sure it gets made to a Sticky. Even is you want to do just 1 of the 3, is fine. Maybe someone else will do the others.

 

[yevgenievich]

There is already one 134 conversion with sanden compressor. Can modify a bit and include general 134 info. Sanden guide recently posted also has trouble shooting info

Any of you AC knowing guys that want to do a real good write up How To thread, in good detail with some pics and such, we could sure use it here on GMSB. Actually could be 3 different threads. #1 Recharging or adding Freon, #2 Conversion to R134A, and #3 AC Troubleshooting. Anyone willing to take the time to do it, I'll make sure it gets made to a Sticky. Even is you want to do just 1 of the 3, is fine. Maybe someone else will do the others.

 

[HotRodPC]

I'll look for it and look it over. Thanks