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

[b5blue]

Have you ever cleaned out or cleared the condenser tubes? Flushing out old systems can remove potential blockage. 

[John_Kunkel]

Oil in the compressor sump circulates throughout the system and returns to the sump.

[cdr]

Oil in the compressor sump circulates throughout the system and returns to the sump.

How does it do that? the pistons have rings on them., when I sold then back in the day it was VERY important to fill the crank case with ac oil,

[John_Kunkel]

There is only a single ring that serves as a compression ring....no oil control rings, therefore oil can leak back into the sump.

The compressor sump is not "filled" but rather measured with a dipstick.

[cdr]

There is only a single ring that serves as a compression ring....no oil control rings, therefore oil can leak back into the sump.

The compressor sump is not "filled" but rather measured with a dipstick.

LOL, come on John,   Filled with the correct amount, you knew what I was getting at

[AKcharger]

OK so I'm trying to follow this...So I need to remove the compressor, place it on a bench, then remove a plug and fabricate a dipstick to measure the oil???   

[GT]

There is the possibility that the valve plates were damaged.  Easy to do if accidentally filled with liquid vs gas Freon (like turning the can on its side or upside down).  Effectively it hydrolocks the compressor and bends the valves.  The compressor then won't function correctly and can be a pain to diagnose.  

When you reach the point of giving up and replacing the compressor, pull off the heads and check the valve plates.  If they are open at all, rusted or bent they need replaced.  You can find the plates and gaskets on eBay... but it's gonna start getting expensive throwing parts at it... I fixed mine like that once, but it only lasted about 3 mo because of the poor condition.  In hindsight I should have just replaced it as that is what I ultimately had to do.

See if John can post the next page of the service manual he showed above about the oil level.  Right at the bottom it talked about the valve plate assembly...

[GT]

Now that I'm thinking about it I am betting one of the valve plates is damaged.  When you started to fill the empty system it worked fine, as it started getting more full it started to lock up as you described.  If one of the valves (basically a reed valve) is bent, that piston will suck and blow on each stroke...get enough Freon in it and it may pull it in liquid form from the high pressure side as the other piston is trying to compress it.    I hate to guide you on pulling the heads however... hopefully I am wrong.

[AKcharger]

Original Auto Air is right down the road from me in Tamp, I'll pull it off and drop it to them to inspect. It was replaced by the last owner but if they didn't know to pull the EPR valve it's likely more stuff got screwed up

[Pete in NH]

You can check the compressor oil level using the dipstick with the compressor mounted on the engine. The system must, however, not have any refrigerant in it . So, you must first recover the refrigerant. Then you remove the plug shown on the left side of the compressor and use the dipstick to measure the oil level.

The RV-2 compressors are like a little V-2 engine in that they have an internal oil pump and use a combination of pressure and splash lubrication. While some oil does circulate around the system most of it remains in the oil sump. Oil amount and type matter a great deal. For R-12 refrigerant stay with the original 525 mineral A/C oil. For R-134A i prefer POE Ester oil. Do not mix oil types as some combinations form a kind if sludge. For example mineral oil and PAG types.

There is no reason why the system with an good EPR valve will not operate as designed. EPR valves are however, getting very pricey and hard to find. Eliminating the EPR valve and going to the A body cycling system does work However, the thermostat switch probe really needs to be in the evaporator case close to the evaporator fins to prevent things from freezing up. Wrapping the probe around the suction line will likely be a problem even if the thermostat switch is adjustable.

I agree with GT in that the reed valves are likely bent, they are very fragile. I never charge these systems with liquid refrigerant, always letting gas be drawn in slowly. The valve plate assembly kits are P/N 2275204 (left side) and 2275205 (right side) these like the EPR valves are getting rare and pricey. Finding a good rebuilt RV-2 compressor is a total crap shoot. Most of the chain auto parts places sell Four Seasons rebuilts which are mostly of the spray and pray variety, new coat of black paint and little else. If you have a decent core with bent reed valves it may be best to find new valve plates.

I'm not sure what to suggest at this point other than pull the compressor off, empty the oil whatever is in there from the compressor and check the valves. Flush out the system, replace the receiver/drier and start with a clean system with the proper amount and type of oil.

Good Luck and keep us posted.

[John_Kunkel]

There is only a single ring that serves as a compression ring....no oil control rings, therefore oil can leak back into the sump.

The compressor sump is not "filled" but rather measured with a dipstick.

LOL, come on John,   Filled with the correct amount, you knew what I was getting at

I was agreeing with you, adding oil from a can through the refrigerant charge port is the wrong way.

[cdr]

There is only a single ring that serves as a compression ring....no oil control rings, therefore oil can leak back into the sump.

The compressor sump is not "filled" but rather measured with a dipstick.

LOL, come on John,   Filled with the correct amount, you knew what I was getting at

I was agreeing with you, adding oil from a can through the refrigerant charge port is the wrong way.

10-4, sometimes I misunderstand how things are typed out 

[AKcharger]

OK guys new Compressor is on-hand and I was going to swap it out but want to confirm
- Service oil though that lil' port in the bottom. I'll make a dip stick and use ester oil (R-134)
- Confirm NO OIL gets introduced on low or high side (if so why do they make it in cans to service it that way!
- Any other suggestions?

[AKcharger]

OK guys new Compressor is on-hand and I was going to swap it out but want to confirm
- Service oil though that lil' port in the bottom. I'll make a dip stick and use ester oil (R-134)
- Confirm NO OIL gets introduced on low or high side (if so why do they make it in cans to service it that way!
- Any other suggestions?

Bueler...Bueler..

OK the compressor came with oil already serviced per seller., but for warrenty need to swap out dryer and expansion valve again, those due in monday and have system evcauated and reservice this week and cross fingers.
Swap went fine, one curve ball was new unit did NOT have woodriff key, that was a mini hassel to swap over

[GT]

So are you all fixed up now?   Get a chance to pull the heads on the old unit for a look?

[AKcharger]

So are you all fixed up now?   Get a chance to pull the heads on the old unit for a look?

I like your optimisim sir!  No old one is in a box still, havent got time to play with it.

As for A/C system I took it in to my local shop to have it evacuated and serviced and...compressor locks up again  The only light in the tunnel is they said it locked up at 3.4 lbs of 134 but according to the conversion chart its supposted to have only supposed to have 37.8 oz so they  over serviced it (and I gave them the chart too). I'm just hoping they didn't ruin the reed valves on THIS one.  I guess I'll try it my self and see what happends, if the valves are bad the vales are bad not hurting anything

[John_Kunkel]

In the end, you will probably find that you'd be money/time ahead if you'd bought your own gauges and vacuum pump and learned to DIY.

[AKcharger]

In the end, you will probably find that you'd be money/time ahead if you'd bought your own gauges and vacuum pump and learned to DIY.

[AKcharger]

OK mostly good news...I have A/C!
Serviced 2 1/2 cans and that did the trick, blows nice and cold (down to 46° @85° abient) so the system is operational again  

Bad News is after the 1st can the clutch started to fail again and not rotate the compressor, but I didn't panic. In my clutch trouble shooting I shot power from the wire going to compressor, it was 10.38V...a decent drop but I didn't think it was signifincant, it is appearently. I jumpered 12V direct from battery and clutch engaged strong and I continued serving. So  A/C is opertional BUT I need to rig up a seperate on/off switch while I track down where I'm loosing power, I susperect some corrosion at a switch or junction

So for thouse following the "wierd" stuff
- Bad compressor or valves
- EPR valve still installed
- Old shrader valve broken off and clogging low pressure line
- 10.4 V as opposed to 12 not letting clutch hook up

[b5blue]

Try installing a relay for now. Activated by clutch 12V+ and fed off battery 12V+ you won't need to add a switch.  Congratulations! 

[AKcharger]

Try installing a relay for now. Activated by clutch 12V+ and fed off battery 12V+ you won't need to add a switch.  Congratulations! 

Oh!  hey that would work wouldn't it? I happen to have a few spare Bosch relayes left over from Headlight mods...good call!

[cdr]

Try installing a relay for now. Activated by clutch 12V+ and fed off battery 12V+ you won't need to add a switch.  Congratulations! 

Oh!  hey that would work wouldn't it? I happen to have a few spare Bosch relayes left over from Headlight mods...good call!

I have a relay on mine also

[Nacho-RT74]

Or simply clean terminals between switch and clutch. It gets 4 in total:

-plug at control unit pigtail
-bulkhead
-presostatic switch at dryer
-clutch pigtail.

That's what I would do instead adding more stuff around.

Also the acc terminal from A/C harness on back of fuse box, which is intended just for the clutch function.

[AKcharger]

Relay installed and works great. So mostly good news with bad. Took car out to run some errands for about 20 mins of driving. While driving temps on MAX A/C from 37° down to 31° so it's cooling alright, I even had to turn it down a bit. Once home I noticed it wasn't as cool hit it with temp gun and it was 58°. I figured it might be freezing up  and looked under the hood and noticed clutch was doing it's slipping thing again  I let it sit about 10 min started it up and all was fine, temps back in the 30's

So I'm going to call the system operational but as a winter project I'm dropping the A/C box and having it gone through and having the hoses remannufacted. I can only think theres a blockage floating around somewhere in the system

- Nacho I gave your idea a try and at bulkhead 11.54V, pretty good! I cleaned the connector and at the terminal 10.16V That's not gonna work and I'm not ready to tear into the harness for put relay in and 11.95V  I'll play with it more later when I pull the box

[Nacho-RT74]

Well, is just because I hate get all the car "relayed" "randomly" all around. I like relays but to make a clean job will require a full wiring network redesign and locate a bank of relays, just like modern cars!

Sure is just my opinion and personal taste LOL.

That voltage on bulkhead is REALLY quite good. The next steps could be easier, at dryer switch. Anyway, the A/C harness is really easy to make. Just 3 wires sections, two blue to the clutch and one green to the blower is available repro thought, but having the skills ( and I know you have ) is pretty much easy.



( I think this harness is missing the presostatic switch section )

I mean, because the clutch actually don't get a load to get worry about the need for a relay, but I understand is being used to save the voltage decay along the wire due the actual wiring conditions. The correct proceeding is fix the line.