New AC Compressor not engaging (even with solid r134 pressure) (1 Viewer)

[danob]

Just dropped a Napa rebuilt AC Compressor & new dryer in my 83 FJ60. PO had already done an r134 conversion, but old compressor's front seal gave out on me.

So... installed new Compressor & dryer, new seals on most line joints, added r134 friendly oil to both, did an old-school "quick-purge" of lines (compressed air, cuz I'm broke). Got cans of r134, tried to bring the pressure high enough for compressor to engage, but it never does.

My ac fuse is not blown, got strong steady pressue for 24 hours now, but don't know what else to try before spending more $$ for an ac pro to resurect it... Any thoughts? Searched the forum here for over an hour, lots of info, but nothing nailing my issue...

 

[SARCruiser]

Is it possible you overfilled it? At static (compressor off for some time) the high and low side PSI should be the same. If not, there may be a clog or other interference in the system. You can reference this chart for a "base-line" pressure at different ambient temperatures: Refrigerant pressure temperature charts for r-22, r-12, r-134a used in reciprocating process chiller systems

Have you checked the a/c relay? The fuse may be good but the relay could be out.

 

[Wile E Coyote]

Since you know there's refrigerant and oil, apply 12v directly to the compressor clutch to test it.

 

[danob]

- I did follow the pressure recommendation on the r134 container per ambient temperature.
- When I push the ac button, I do hear the relay click under the dash (yet nothing happens). But I did not verify if indeed I do get current out of the relay...
- I will connect the compressor directly to the batery for a quick test this evening to rule out compressor issue (but it is a fresh reman Nipo)

I wasn't sure if I had to dig deeper with $ and possibly replace the Expansion Valve. Or if that would even help at all with compressor clutch not engaging.

 

[dallen341]

Did you evacuate the system before charging? If there was air in the system then there is the posibility of moisture too (which can freeze). Just an unrelated thought...

 

[1972FJ55]

A few questions:

Did you get the R134a into the system and if so, how much?
I'm not sure what "strong steady pressure" means. Do you have any gauge readings?
Did you pull vacuum on the system before charging it? If not, you're going to have a bunch of air in there, so the system will not operate correctly. The compressor will rattle, it won't cool very well, and it only takes 2% air to see these effects.
Check the lead going to the compressor to see if you have 13+volts with the engine running and A/C on.
Check the clutch air gap, the distance from the front hub to the pulley, there should be about .020" space inbetween.
Unlikely that the expansion valve has anything to do with the problem.

Hope this helps.

 

[danob]

Evacuate - let's just say "somewhat"... Took the poor mans approach. Disconnected lines in 4 spots, blew air through all. Reconnected everything, then started filling r134 from low side while holding high side valve open. As soon as r134 made it's way around to high side, I let the high side valve close, and continued filling until I got the correct pressure. Far from a professional vacuum approach, but was hoping this would be enough to get me through until funds picked up.

Note: This is my daily driver (work, groceries, baby hauler), and we already had a few days above 100 F earlier this week in Phoenix, so I am desperatetly trying to resurect my ac.

 

[Wile E Coyote]

Blah blah blah...
Hope this helps.

Yeah, like you would know anything about this kinda stuff
(It's actually a good thing he's chimed in OP...it should offset any questionable advice from us shadetree types)

In rereading your first post OP, I can't help but fixate on the impression that you dropped the coin on a new comp and drier but didn't pull a good vac on it afterwards? That's an almost guarantee you'll be back doing this VERY soon, assuming it ever works decently to begin with.
Rent a venturi vac pump from Autozone, Checker, etc. along with if you need it, a real gauge set...it won't cost you a dime if you take the tools back.

 

[danob]

A few questions:

Did you get the R134a into the system and if so, how much?
I'm not sure what "strong steady pressure" means. Do you have any gauge readings?
Did you pull vacuum on the system before charging it? If not, you're going to have a bunch of air in there, so the system will not operate correctly. The compressor will rattle, it won't cool very well, and it only takes 2% air to see these effects.
Check the lead going to the compressor to see if you have 13+volts with the engine running and A/C on.
Check the clutch air gap, the distance from the front hub to the pulley, there should be about .020" space inbetween.
Unlikely that the expansion valve has anything to do with the problem.

Hope this helps.

Ok, you just scared me a bit about 2% of air in my system being enough to cause negative effects... If I do figure out that it is an electrical issue, but doesn't cool down properly, I will then try to get a proper vacuum done at a shop.

As for pressure reading, unfortunately, the only thing I have to rely on is the cheap pressure gauge that comes with r134 refill kits.

 

[Wile E Coyote]

Blowing air through the system won't do crap for removing moisture, hell depending on the quality of your shop air it coulda ADDED to it. Pulling a good vacuum will remove moisture, however. The vacuum created lowers the boiling point of water such that it evaporates and gets sucked out...It's also a decent way to test for leaks without wasting dough on refrigerant.

 

[danob]

Ok, so my plan of attack after reading all replies...

a) Keep chasing down the electrical issue to get system functionning (will inspect relay, switch continuity & resistance at pressure switch).
b) Definitely need proper vacuum & recharge done as soon as I can

Wile-E, in regards to me dropping the coin for compressor & drier, but not paying for vacuum... what can I say, I'm tapped out, and doing the best I can under my circumstances. If I have to pick between renting equipment or putting food on the table for the fam, well, a man's gotta do what a man's gotta do

 

[Elbert]

what happens now when you "hot-wire" the compressor?

you will not get it to work right until you pull a vacuum on the system as others have noted...I think it would be good to stop until you are able to do that and then get it charged. Its also good practice to always replace the dryer/accumulator. vacuum and charging should happen as part of two step process all at the same time/same event.

 

[Wile E Coyote]

Danob, not tryin to bust yer chops man, just wanting to impress upon you the fact that a half-done job may end up costing you twice as much. Thats especially painful since the vac and gauges would cost you nothing to rent. Check out www.aircondition.com for pages of detailed advice on automotive ac systems.
I spent a couple years daily driving a Dodge Ramcharger around Lake Havasu w/o ac...I can relate.

 

[danob]

All right guys - I took all of your advice into consideration (I would be lost without this forum). Thanks again for all your input (and no worries Wile-E, it was all good advice).

Since the new compressor had never been started, I dropped my FJ60 at a shop this morning for a vacuum & r134 refil. It held the vacuum no prob, so they refilled it. They could not get it going by pushing the ac button. I told them I didn't want to pay for voltage troubleshooting on their end, and to simply hot-wire the compressor to finish their work, and they were getting 41 degrees at the vent.

So I guess I will be back to chasing the 12v power issue this evening. But at least I know that as a last resort, I could simply install a relay & switch straight to the compressor. But I still would feel better knowing everything from the factory worked (I hate band-aid fixes).

And if any of you have clues, I'm all ears

 

[kevinmrowland]

If you focus in on the AC amplifier you can troubleshoot all your wiring concerns from there.
Do you have the FSM?
Can you borrow one if not?
You need it.
Anyway, the AC amp is going to be the first real step. From there try jumping out the various circuits until you can get it narrowed down.
You can jump the yellow wire to the black/white wire to manually engage the clutch. (the yellow wire is the signal in from the switch, BW goes out to the clutch, simple as that)
From there I would identify the pressure switch circuit, it goes up and over the top of the AC box and enters where the hard lines come out the front, unplug it and jump the wires together, that pretends the pressure switch is engaged. (I have had the pressure switch suddenly stop working by doing nothing other than draining the system)
Keep going from there, don't forget about the coil signal, the amp needs to know the motor is spinning at a fast enough RPM to engage the system, it's nice that all the circuits can be assessed right from the front of the box.

 

[60 toy ota]

subscribed, same problem