[tkaauwai]

Background: A/C has been blowing warm air for months. A couple weeks ago I added a can of refrigerant, and the compressor kicked on, but the A/C didn't stay cool for more than a couple days. Changed the o-rings at the compressor, and tried to add refrigerant back into the system, but the compressor isn't going on and the refrigerant isn't being sucked into the system.

I've read many posts that say you can force the compressor to go on by jumpering the low side switch, but none of the posts I read say exactly how to do it. There's 4 wires (white, red, black, blue). Which ones do I jumper? Also, is there a way to jumper the compressor from the A/C relay? If so, which connections do I jumper (again, there's 4).

Thanks for the help!

 

[frogsthatmoo]

"Jumper" is not the correct verb for what you're asking. Just to clear that up....

Anyways, the low pressure sensor that you're asking about (and it's called shorting or closing the circuit) is located by the drier canister I believe. That's where it was on my Legacy BK. But be forewarned. There might be a reason your AC compressor isn't kicking on. Sure the sensor could have gone bad, but be careful you don't damage your compressor.


The drier - receiver canister is located next to the passenger side strut tower. It's silver. You can see it in this picture next to the 90 degree intake elbow. That's what you're looking for to find the sensor.

 

[tkaauwai]

Thanks, but I know where it is. My problem is that there aren't simply 2 wires on the connector -- there's 4 as previously mentioned and I want to know which ones to connect in order to test the operation of the compressor and, if it works, possibly get the system to suck in refrigerant.

Through my many searches, I've seen many people say they've "jumpered" the connections in order to force the compressor to operate, but I haven't seen a description of which wires to connect.

 

[frogsthatmoo]

Oh, you were talking about the AC relay so I didn't know.

Have you actually gotten the pressure checked by anyone? I know you added refrigerant, but that's kind of a blind statement without knowing whether there's actually stuff in the system.

 

[tkaauwai]

Well, I'm basically asking how to force the compressor (or I guess the compressor clutch?) to go on so I can test if the compressor is bad.

I did not get the pressure checked by anyone, but before changing the o-rings at the compressor I quickly tapped the low side valve and there was nothing (no hissing of refrigerant escaping) -- even though I had put a can of refrigerant into the system a couple weeks ago.

 

[frogsthatmoo]

Ok, let me stop you right there. I think you may have lost a lot more R134 than a can could replace. I highly recommend you get the pressure checked by an actual mechanic before you get the compressor going. Those cans are meant to bring a "low" system back up to normal pressure. Not fill it all back up.

This is just my 2 cents though. Do what you like, but this is what I would do first and I'm on my third Subaru.

 

[tkaauwai]

Thanks for your thoughts, but I guess this means you don't know the answer to my original question of how to force the compressor to engage for a 2003 H6 3.0. Anyone else?

 

[nipper]

When someone warns you you may have an over filled system, they are trying to do you a kindness.

Get a set of pressure gauges so you know what your dealing with. If the system is low, or too high, you can damage the system if jump the compressor.

Get a meter and test the compressor clutch for resistance. If it shows it is open it is bad. It is rare for the clutch on the AC to go bad on a subaru. This year H6 i think also had an issue with porus AC hoses.

 

[jp1203]

When someone warns you you may have an over filled system, they are trying to do you a kindness.

Get a set of pressure gauges so you know what your dealing with. If the system is low, or too high, you can damage the system if jump the compressor.

Get a meter and test the compressor clutch for resistance. If it shows it is open it is bad. It is rare for the clutch on the AC to go bad on a subaru. This year H6 i think also had an issue with porus AC hoses.

Exactly. There's oil in the refrigerant and it won't run if it's too low for a reason. If you force it to ignore the low pressure and run, you risk burning it out even if it works now.

I'd have a proper evac and recharge done and the shop can put a dye in to find a leak if there is one. Most of us simply don't have the equipment to deal with A/C stuff, and it's tough to get it right without it.

That said, if you're losing refrigerant take a look here: http://www.subaruoutback.org/forums...efrigerant-repair-5-less-15-minutes-less.html

 

[tkaauwai]

Thanks guys. That thread you linked started me on this whole journey. However, am I to understand that after replacing o-rings at the compressor and hooking up a can of refrigerant to the system that the system simply should suck in the refrigerant without being vacuumed? I've tried adding a can of refrigerant after changing the o-rings, and a bit of the refrigerant went into the system but the compressor doesn't kick in and it won't suck in any more refrigerant. I know the compressor won't go on if the pressure is too low, but I've read other threads that mention the refrigerant won't be sucked in if the compressor won't go on (kind of a catch 22).

As far as testing the clutch for resistance, at what pins am I measuring the resistance? The connector on the compressor has 3 pins. And what should the resistance be? By the way, when I tried to remove the connector from the compressor, the connector's plastic was so brittle is crumbled and fell apart, exposing the electrical parts. It can still plug back in, but it doesn't look so good and I'll eventually have to deal with that.

 

[jp1203]

Thanks guys. That thread you linked started me on this whole journey. However, am I to understand that after replacing o-rings at the compressor and hooking up a can of refrigerant to the system that the system simply should suck in the refrigerant without being vacuumed? I've tried adding a can of refrigerant after changing the o-rings, and a bit of the refrigerant went into the system but the compressor doesn't kick in and it won't suck in any more refrigerant. I know the compressor won't go on if the pressure is too low, but I've read other threads that mention the refrigerant won't be sucked in if the compressor won't go on (kind of a catch 22).

As far as testing the clutch for resistance, at what pins am I measuring the resistance? The connector on the compressor has 3 pins. And what should the resistance be? By the way, when I tried to remove the connector from the compressor, the connector's plastic was so brittle is crumbled and fell apart, exposing the electrical parts. It can still plug back in, but it doesn't look so good and I'll eventually have to deal with that.

Not sure about the electrical part, Nipper might be of help there.

But, in my experience the pressure doesn't have to be terribly high for the compressor to run. It will run long before there's enough refrigerant in the system to produce cool air. When I bought my 2004 H6, the A/C was totally devoid of refrigerant. I recharged it based on what the capacity was listed as (can't remember at this point what it was), and the compressor kicked on relatively soon after I started to add refrigerant. It's tough to go by pressure because it varies by temperature, is really supposed to be checked when the engine is revved to a specific point, the gauges they sell with the do it yourself kits are really terrible, etc.

 

[frogsthatmoo]

You want an answer? Bridge the green and yellow wires with a paper clip or a fuse. I've done it before.

 

[frogsthatmoo]

Conversely, you could just apply 12v to the compressor itself and engage the clutch manually. It's a pretty simple circuit. Please report back though, I'm eager to know what happens.

 

[signage]

If you opened the system to the outside air, You have induced moisture into the system. The system now has to be evacuated to remove this moisture. You most likely also lost oil when you opened it or through the leak! So if you get it to work it most likely will not last very long without being serviced correctly.

 

[frogsthatmoo]

lol.... I wonder what happened to his AC

 

[nipper]

Maybe he went poof?

 

[idosubaru]

If you opened the system to the outside air, You have induced moisture into the system. The system now has to be evacuated to remove this moisture. You most likely also lost oil when you opened it or through the leak! So if you get it to work it most likely will not last very long without being serviced correctly.

this is incorrect. pulling a vacuum is ideal but not necessary at all. fairly easy, particularly on a Subaru, to go hundreds of thousands of miles with no issues. they're A/C systems are rather robust. i wouldn't borrow this notion and use it on other manufacturers though, i only do Subaru stuff. but i've done it countless times with no issues and hundreds of thousands of miles - with zero failures, that's pretty good for many DIY home people that don't want to pay shop prices for A/C work.

the little bit of air that gets into a system is easily mitigated but i'm not going to explain it all here.

 

[cardoc]

The air and moisture needs to be removed to insure proper function of the compressor and efficiency of the refrigerant. Water needs to be removed to prevent corrosion and sludging from within, especially the compressor. A proper oil charge is also needed. Not enough oil or too much is a bad thing. Not enough, bye bye compressor, too much, the refrigerant can't move proper and there will be an extra strain on the compressor. Those compressors last a long time, (300k on my 99) and are expensive for a reason. Not to mention hard to find outside a salvage yard.

As far as jumping, it can be done from the relay. A test light will tell if you are getting the battery current from the fuse, ground at the compressor clutch, ground from the ECM and power from the ignition. Clamp on the batt + and probe on a negative active ground, opposite will show batt +.

Jump the pin from the compressor clutch to a batt + at the relay and if the clutch clicks, its good. With the engine running, check for the ground from the ECM with the AC switch on and batt + on the other two terminals. If you are getting ground from the ECM, batt + is all good and the clutch kicks on, your problem is refrigerant. If you are not getting a ground from the ECM, you may have a bad pressure switch.

 

[burnout8488]

It just makes no sense for the OP to be working on their A/C system if they have no prior experience, and haven't properly studied up on how to do everything correctly.

Going about this one step at a time, then coming back to ask more questions is not the way to do it. Understand everything you'll need to know, now and in the future, is key to do the job properly.

 

[cardoc]

The only way to learn anything is through trial/error. You give someone the information they want and if they screw it up, it's on them and they learn from it.

Had a heavy mechanic one time in the field at a crusher/hot plant site working on a 992 loader. He was to remove the lift cylinder so it could be rebuilt. He was told numerous times and shown how to do the job. He was hard headed. He parked the loader, lifted the bucket, set the RR ties for blocks and proceeded to loose the hydraulic hose on the cylinder while we watched. He broke loose the pressure line while the lift arms were still up. We let him. He got drenched and scared the life out of him at the same time as the lift arm came down.

He wasn't in danger, we saw that prior. He had the blocking set, just didn't set the arms down. Then he loosed the wrong line first. He was mad, but he never did it again. And we got a good chuckle out of it.

Sometimes you let people do what they want to do in order to learn from it. Whether they get it right or wrong.