Air Conditioning help...it's serviced but blows hot, where do I start?

[AKcharger]

OK guys worked it a bit more today

Attempt #1  (failed to hook up high side at 1st)
Low pressure side static - 105 psi
Low side car running A/C on 33psi
high side got hot no temp change on low side
hooked up high side and started car again and A/C clutch was Slipping ony occasionally rotated compressor pump

Attempt #2 four hours later
Low pressure static - 68psi
High Pressure static - 110psi
tried A/C again but clutch still slipping low pressure stayed the same but High side went up to 130psi

So questions:
1) 1st I have to fix clutch is there a rig/adjust that may be off our do I just get a new clutch assembly?
2) is there enough info to make any guesses yet on where to go next?

Thanks!

[Nacho-RT74]

I remember when I got one of these, NOS ( without the coil ) on $40 or so on eBay.

https://www.ebay.com/itm/283615572400?epid=656750491&hash=item4208ce31b0:g:MqAAAOxy0zhTKxGo

Then I found 3 NOS coils locally in Vzla. Mine was perfect, but just for fashion ( and for a new looking wire ) installed one of them on my car.

On a side note, I think the York clutch is the same than the RV-2 so maybe searching it for York will be cheaper ( not the pulley but the clucth itself ) it happens the same with the front seal. RV-2 and York uses the same front seal.

[AKcharger]

New clutch and Bearing on-order...stby

[AKcharger]

OK, replaced Clutch and it's doing the same thing, slips and before I could get my wife to shut it off I thought I saw a spark too! so now I'm thinking the internal pressure is too high or the compressor is seized, any suggestions before I just go blow coin on a new compressor??

[green69rt]

Can you turn the compressor by hand?  Thru several revolutions.

[b5blue]

  With the engine off, loosen the belts and put 12V + to A/C clutch. If the clutch activates and stays stable see if you can turn the compressor in the direction it would normally run. 

[AKcharger]

Ah! good advice B5blue was wondering how I was going to engage the clutch
OK so with clutch engage it locks up and I can spin it in either direction. One Half its somewhat easy and the other half it gets harder...does this tell me anything?

Thanks in advance!
P.S. Working an Air Cleaner issue, that's why it's changing from black to Orange back to black lol

[b5blue]

So the system is cycling on and off by it's self. Find the pressure switch by back tracking the compressor clutch wire and jump it. Do a short test run just to see what happens. 

[AKcharger]

So the system is cycling on and off by it's self.... 

Well I wouldnt say it's "cycling" it's more like a presure block that's locking up the compressor. turns a few time stops, tries to move a bit, stops ect. I'm beging to think that valve is still in the low pressure side, the one your supposed to remoed with R-134. there's no sign of any pressure switch anywhere

[b5blue]

All this stuff your dealing with is why I just went with Classic Auto Air. I don't know enough about the factory set up. 

[b5blue]

Yea if the clutch is staying "on" and the compressor is getting halted that is another can of worms. The switch I was referring to prevents the system from running with pressure to low. 

[John_Kunkel]

The pressure switch is usually screwed into the side of the accumulator (yellow arrow).

I doubt if the presence/absence of the EPR valve in the compressor would cause a lockup.

Forget the clutch, if you put a 1/2" wrench on the bolt in front of the clutch and turn the bolt clockwise, do you still experience the lockup part way through a couple of turns? If so, it could be a pressure lockup but the only way to know for sure is to dump the refrigerant and see if it still does the same thing with no refrigerant in the system.

[AKcharger]

B-5 - I agree with the classic option if it never had an A/C system, im real happy with the set up in my '72 but I'd hate to gut out a complete original system. Copy on switch, it's supposed to be installed when you remove the EPR valve
John Kunkle - great to hear from you. Well no need for wrench I can turn it by hand and as said above spins smooth, gets hard then spins free. I don't recall seeing a switch...we're talking about the dryer right??

I'll have system purged and see if it spins and see if that EPR valve is there

[Just 6T9 CHGR]

Following this as one day I might try and get my factory system working again 

[John_Kunkel]

Well no need for wrench I can turn it by hand and as said above spins smooth, gets hard then spins free. I don't recall seeing a switch...we're talking about the dryer right??

That sounds like normal hand operation, it gets hard on the compression stroke and then frees up after that. Locking up in operation usually means the compressor is trying to pump liquid instead of the gas that should be in there which could mean the evaporator isn't working efficiently....could be the EPR valve.  

Yes, switch is on the accumulator/dryer.

[AKcharger]

Had system evacuated and yup..ECS valve was is still installed. removed valve and thermostat on order...STBY

[b5blue]

Here we go. Your gonna love A/C! 

[AKcharger]

Oh, with the EPR valve removed the compressor spins over fine with clutch engaged, no lock ups so that EPR valve WAS the issue there. anyway therostat kit on order, I'll hook it up, get it serviced and report back in a week or two

[Nacho-RT74]

So it was EPR valve stuck.



If you search for the Master tech service conference, A bodies got the thermostatic switch located over the A/C box with the sensor bulb inserted into the evaporator. A bodies compressor cycled the A/C clutch on and off to keep the Temp, just like any regular refrigerator, while B bodies used the EPR valve keeping temp by the refrigerant pressure over the temp variation, so compressor never turned off.

I'm planning on emulate the A body setup on my 74 someday in the future since I'm already using 134r refrigerant. I hate that ugly temp sensor switch mounted on engine bay. I guess getting the real temp sensing into the A/C box will help on a better temp control of the cab, which is what all we want.

Full size bodies used an ETR valve instead the EPR which is a mix of A and B bodies. If the ETR valve was available I think this could be the best option.

[Nacho-RT74]

https://www.mymopar.com/downloads/mtsc/295.pdf

A body is an adjustable temp switch by the control lever, but our B bodies get a temp control by the hot water flow. So a fixed temp switch should work. Or an adjustable one but set at an specific temp, not conected to the control switch. So you could try diff temp setups to suit better your needs.

[AKcharger]

Wow! that's good info there!! thanks Nacho!

[AKcharger]

Update:
- "Original Air" Thermostat kit wired in. Simple enough, cut power wire to clutch and route though switch, coil wire around outlet tube and seal with thermal tape
- Serviced system...freon super slow to enter system, found an old schrader vale jammed in ridged hose
- Removed forgien object and serviced freon...after about 1/2 a can with engine running the clutch started locking up, like last time
- My pal ( A "real" mechanic) suspected voltage might be week and sure enough wire going to clutch 10.68V so we jump the wire for pure 12V+ and the clutch is much "stronger"  but when we start it the clutch still locks up/slips
- Jumped Clutch wire to Batt and tried to service with ening running that way..no-go, still locked up

So I'm thinking there must be an internal fail in the compressor that's causing a vapor/liquid lock. Before i spend $$$ on another compressor any ideas what to try>>

[Pete in NH]

Hi,

Any idea how much oil is in the compressor? Way too much oil could cause a lock up.

[AKcharger]

Hi,

Any idea how much oil is in the compressor? Way too much oil could cause a lock up.

No, We weren't sure if or how much oil was in there so we just put another can in. is there a way to drain it?

[cdr]

Hi,

Any idea how much oil is in the compressor? Way too much oil could cause a lock up.

No, We weren't sure if or how much oil was in there so we just put another can in. is there a way to drain it?

Pretty sure the RV2 compressor has a crank case & that is where the oil goes, NOT in a oil charging can