Douglas Brown

When it is cool in AM clutch kicks in and out great. Drive it in PM when temp 100 deg. it will not engage, just screams, major slippage.?????
I know thing expand but for a clutch not to engage???
Any one have similar experience.??
It's a new system.
I know I have to change out the clutch on the A/C.
DB

'75

In the morning when it's cool, the pressures are lower than when it's 100 deg out. Is the belt in good shape and adjusted correctly? Also has there been work on the ac lately, possibly an overcharge? do you have AC gauges you can hook up and wee what;s going on?

Douglas Brown

Yes belt in new condition. Adjusted by hand but good tension maybe 1/2 inch when pushed down with one finger. NO work other than I installed it new, cleaned and flushed every part and dried it out in AZ heat during summer. New o-riings for 134a. added oil as per specs. Added maybe 3 lbs of 134a. (3 cans @ 19oz each= 47 oz. / 3lbs = 48 oz) NO, NO gages yet. or vac pump.
Started up car this afternoon. turned on switch. went to connect elect. lead to comp. clutch starts to spin as normal no noise, then it starts to screech and then spin then screech and then spin off and on then screech. clutch turns as it screeches.
Over charge?????
SO I gather it may not be a magnetic clutch but pressure in system? causing the pump not to turn>????

DB

'75

I sounds like the clutch is trying to do it's job, but there is too much resistance to it. The screech is likely belt squeal, hopefully the compressor is not locking up.

Douglas Brown

At first I thought it might be belt slip, but no, no burn or rubber smell, just metal to metal screeching.

If it is not pumping and engaging then there is no way check what it is doing other than to check the current pressure in the line. which will reflect the out side temp. yes?

If I hook up the gage and all I get screech, then I can not get a read???
bad pump.

Douglas Brown

Tomorrow I'll pick up gage....

Douglas Brown

Upon reflection on my install, flushing the parts, and installing the A/C comp. and 134a with out vacuuming it first may be my problem. Could be there is something that I did not get out that causing the pump to stick. If there is no other reason for the clutch to screech as it spins. then there is something in there. I'LL have to get a new pump.

'75

Having a little moisture and air due to not vacuuming shouldn't cause the compressor to fail(although it will certainly effect the cooling ability). Debris from a previous failure or a defective rebuilt compressor is more likely. Try turning the compressor clutch by hand, if you end up changing it, be sure to replace the dryer and flush the system.

Douglas Brown

Well we can rule out previous failure, there was not one. Rebuilt yes this possible. Spoke with A/C tech. locale shop he said when comp. low on refrigerant it will act like this due to a leak??? SO, I picked up a gage set and a few cans of refrigerant with dye in them and uv glasses w/light.
I will check temp and pressure then recharge system and see what happens.

Does refrigerant have an odder like gas and other fluids have????

'75

It has a slight odor, not strong at all.

Douglas Brown

I noticed a strange odor in the garage prior to the problem I am having.

So I may have a leak???

Douglas Brown

Attached gages this am opened all valves ..76 outside temp..low side reads 95 high side reads 95

started motor, run at 1,000 rpm, reach temp of 195-200, as soon as I connect electrical connection to clutch it screeches.
gages...low reading 350 + high 130

THIS WOULD indicate a blockage?? on low side???? orifice tube???? or where???

Possibly clogged accumulator or bad check valve on low side in compressor. Check valve not allowing refrigerant to pass.

Douglas Brown

It's been several hours since I shut down the motor, ordered a new compressor and new orifice tube. Gages have equalized at 110, temp in garage 89.

'75

Did you indicate the hi side gauge goes to 350 psi as soon as the clutch kicks in?

Douglas Brown

NO....When I connect elect. to clutch, clutch begins to screech. Low side jumps to and pegs at 350 plus......High side goes to 130.
Clutch never really kicks in or spins freely (Normal) just screeches.
After several hr's of rest both read 110
Does not matter at this point, will pick up new pump today and a vac pump......

Douglas Brown

After removing the A/C pump, I took out the Orifice tube.

This is what I found....NOW I know I cleaned that out. it smells like burnt oil, there is fiber of some sort and metal flakes.

Douglas Brown

'75

You need to disassemble as much of the system as possible and clean/flush all the debris out or you will end up with the same problems. Replace the dryer, vacuum for at least 30 minutes, preferably 1 hr, then add oil and refrigerant. When you vacuum it, the vacuum pump needs to run for the whole time so that as the moisture boils it can be exhausted out through the pump.

Douglas Brown

Yep....will go as far as possible today...nephew comes over tomorrow he can help remove hood......

Douglas Brown

After a few days of removal of all lines, flushing, reassembling, I can secure the pump and vacuum tomorrow.