A/C wooooos

Thanks for looking!

86 740. a fairly new compressor, since the compressor went in.....the compressor turns at idle and works fine, but as i drive it cuts in and out. Low on juice?

Could be over filled. Need pressure readings.

Probably a little low on refrigerant. Get a cheap gauge like this one from Walmart or a local auto parts store: https://www.walmart.com/ip/EZ-Chill...SpJSUvf4nqZ7HP4ArVYaArfXEALw_wcB&gclsrc=aw.ds

I have two "professional" gauges although I just use the one I just linked when I do refills every couple months. It's real handy. You know you're low if the compressor cuts out when the engine is accelerated and the needle is almost out of the green (on the low side). It will spike up when the compressor disengages.

If low, you can open the valve for a split second to let the air out of the hose so you don't get any in the system, add a can and fill up with a bit of R-134a in when the compressor kicks back on. I'm assuming you have been converted to R-134a if you have a newer compressor, make sure you are though.

ODDmanout said:

but as i drive it cuts in and out. Low on juice?

Click to expand...

Cuts in and out, or "cycles" like a compressor should do? (They are not meant to run continuously like a fridge)

I will get the cheap gauge as shown above. On my current cheap gauge it shows 55 psi before compressor cuts out, just on the bottom side of the red line.

It is my understanding that a compressor will cycle if the refrigerant is not being heated back up fast enough. Not the issue here in lower MO.

what was the temp outside. That sounds high to me? If your in mo. I know temp been in the 70s-80. Which would make that reading to high in my book. When you put new comp. on did you vacuum the system? If you didnt then thats a huge problem, air in the system will play havoc on everything and cause high pressures and low cooling.

ODDmanout said:

Thanks for looking!

86 740. a fairly new compressor, since the compressor went in.....the compressor turns at idle and works fine, but as i drive it cuts in and out. Low on juice?

Click to expand...

how long have you observed it when it's idling? As was mentioned, it should idle off and on while driving or on idle too. IOW the issue is not when you're driving.

90Volvo: Here in Joplin, not far from you. It does seem high. What kind of PSI am I looking for? Yes, I did vacuum it.

Brickyard92: Have not done much observing at idle. It has that stupid ZF transmission, so i try not to let it idle in park much.

Double-check the compressor ground wire. 2 years ago I had a brand new compressor installed and the ground wire was not tightened to the bracket enough.
It took me 3 months to figure out that it could have been an easy fix.
The compressor shorted out and I took it back to the shop. Thankfully it was still under warranty.

ODDmanout said:

90Volvo: Here in Joplin, not far from you. It does seem high. What kind of PSI am I looking for? Yes, I did vacuum it.

Brickyard92: Have not done much observing at idle. It has that stupid ZF transmission, so i try not to let it idle in park much.

Click to expand...

Here is a scale you can go by as a reference. What I like to do is find out the ac capacity and put it in close to that amount. If the system been modified then you can use the scale as a reference. What yr. and etc is your volvo? I typically have a house fan blowing on the condenser and have the car up off idle. Im glad you pulled a vaccuum, you might be ok on pressures if you were idle and no fan blowing on it. So comes back to why compressor kickng on and off? Check your ground as mentioned above, redblocks shake alot, Im always finding stuff loose. Im from the Joplin area, my son still lives in Joplin and have a brother living in Webb C. PM about your car, nice to have a volvo fan near by

ODDmanout said:

90Volvo: What kind of PSI am I looking for?

Click to expand...

Systems are different over the years and especially over the ambient temperature range. General starting point at 80-85 degrees should be about 30 psi on the low side.

I am getting 46 degrees vent temp at 82 degrees outside with 30 psi on the gauge. Completely rebuilt system. New compressor, new condenser, new expansion valve, new hoses. Been that way since all work 6 years ago.

Don't think I will mess with it.

As I was testing and mulling the blower motor started to shriek, that turned into howl, then it gave up the ghost. Better now then in August. That $5 motor didn't last with rain pooling in the bottom of it, removing all the precious grease.

Thanks for tips and tricks everyone!!

Keep those Volvos rolling!!