Subaru Outback Forums banner

1 - 20 of 23 Posts

·
Registered
1998 Subaru Legacy Outback
Joined
·
9 Posts
Discussion Starter #1
I have a 1998 Subaru Legacy Outback and I'm having trouble with the air conditioning. When I press the AC button on the dash, the green light comes on, and the blower motor is blowing air, but air is not cold. The radiator fans do not come on, and the compressor clutch does not engage. I've checked all the fuses, and they are good. I've also tested all 4 of the AC relays in the fuse box under the hood, and they are good as well. The compressor clutch coil measures about 5 ohms which seems OK. The pressure switch is measuring about 1 ohm, which indicates I have good coolant pressure as well (if I'm measuring that correctly). I don't know what else to look at at this point, and I can't find any sort of wiring diagram for the AC system. Anyone have any thoughts?
 

·
Registered
2012 limited, white, no moonroof or nav
Joined
·
1,698 Posts
Look in the underhood fusebox for a relay. I am not familiar with your particular vehicle, but what you describe fits a bad AC relay.
 

·
Registered
1998 Subaru Legacy Outback
Joined
·
9 Posts
Discussion Starter #3
The fuse box under the hood actually has 4 relays labeled as AC. They are all identical. Each relay has 4 terminals; 2 are for the coil and 2 are for the switch. I measured the resistance of the coils and they where were about 100 ohms, and I measured the switch resistance with and without 12V on the coil terminals. They all seemed OK. Each relay cost about $25 so I don't really want to just replace all 4 to see if that fixes it. If I had a reasonable wiring diagram, I think I could track down the problem.
 

·
Premium Member
2001 VDC/SC One of a Kind
Joined
·
14,318 Posts
Match pins 30 & 87 with the corresponding pins of the relay box for the AC and jump them. If the compressor clutch clicks, its not the clutch.

Look for oil residue or green tinted oil residue around the line connection to the compressor and service valves.

The relays are for the fans, blower and then clutch. You want the AC clutch.

Majority of Subaru AC issues is due to a leak in the system.

System hold 1.3lbs R134A. Don't forget a couple oz of oil.
 

Attachments

·
Registered
1998 Subaru Legacy Outback
Joined
·
9 Posts
Discussion Starter #5
Thank you for the wiring diagram, cardoc. I haven't been able to find that anywhere, including my local library (not that its a great resource anymore).

I didn't know what pin 30 and 87 were on the fuse box, but I was able to figure out which of the 4 relays was the AC clutch relay. I shorted across the switch terminals of the AC clutch relay socket, and the the clutch engaged as expected.

Then I started looking for the oily substance on all the lines and fittings and I did find some light weight oil on the high pressure fitting to the compressor. There wasn't much of it, and I couldn't tell if it was green or not. I only found it by feeling around to the back side. I'm guessing this means I have a leak here. I didn't find any oil anywhere else along the lines.

I found this thread on replacing the o-rings on this fitting: diy-c-air-conditioning-leak-refrigerant-repair-5-less-15-minutes-less. Like it said, I uncapped the schrader valve and gave it a quick press with a screw driver. Nothing came out.

So, I'm pretty sure the system is drained. I can easily replace the o-ring myself. I'm just wondering now if I should try to re-charge the system myself or not. Or, if there is anything else I should replace while the system is empty.

Any thoughts or opinions anyone?
 

·
Premium Member
2001 VDC/SC One of a Kind
Joined
·
14,318 Posts
Some might say I'm the local library. Who knows.

You may as well change both line seals and the service valve stems, can be picked up at Oreilly's or other parts chain with AC supplies.

Its best to have the system evacuated to insure all the moisture is out and then recharge with oil and refrigerant.
 

·
Registered
1998 Subaru Legacy Outback
Joined
·
9 Posts
Discussion Starter #7
Cardoc, do you think replacing the dryer is worthwhile or necessary?

I'll pick up some line seals and stems tomorrow and get them installed.
 

·
Registered
1998 Subaru Legacy Outback
Joined
·
9 Posts
Discussion Starter #9
I got the o-rings replaced tonight, and I bought a venturi vacuum pump and AC manifold gauge from Harbor Freight. I was able to evacuate the system to about 11-12 psi. I'm assuming that will be enough. I'll let that sit overnight and we'll see if it holds up. Then, I'll try charging the system tomorrow evening if I have time. What pressure should the system be charged to? Or maybe I should ask what the low side and high side pressures should be?
 

·
Premium Member
2001 VDC/SC One of a Kind
Joined
·
14,318 Posts
How long did the evacuator run? I would be willing to bet that unless the pump can't pull a good vacuum, if you were to go out and check it now it may be at "0". Meaning there is still a leak. Either your manifold set or somewhere other than the service ports.

If its still at 11-12 psi, then its just the pump. Normally a vacuum pump will pull 20-25 inHg.
 

·
Registered
1998 Subaru Legacy Outback
Joined
·
9 Posts
Discussion Starter #11
I let the vacuum run for about 2 minutes. It went to -11 psi pretty much right away, that then didn't really change after that. For some reason, I couldn't get my compressor outlet pressure higher than about 50psi, so that might also be why the vacuum pressure is low. I just realized that I should have run the vacuum on the manifold gauge by itself (not connected to the car AC system) and see how much pressure I can get out of it. I was running the vacuum from the low pressure side. I figured that was the right side to do it from, but I'm not sure. I'm too beat to go out and check it now, so I'll do it tomorrow.
 

·
Registered
'03 Outback H6-3.0 Black Granite Pearl, base model with cold weather package and cloth seats.
Joined
·
1,061 Posts
Venturi pumps can't create "real" vacuum for an application like this. Needs to be a centrifugal or piston pump.

To vacuum out the system, I'd think you want 25-27 inches of Hg vacuum.
 

·
Registered
Joined
·
7 Posts
Solved

Fixed! I found a sticky relay!

Thank you for all your posted comments. No matter how smart or clever you think you may be there is always someone out there better (in my case several)!
 

·
Registered
1998 Subaru Legacy Outback
Joined
·
9 Posts
Discussion Starter #14
I got a little distracted by life's other problems, but luckily it hasn't been too hot out, and I haven't needed the AC. Now I'm back at it.

Okay, so the good news is that the vacuum holds overnight, so I probably don't have a significant leak. The bad news is that i'm not getting as much vacuum as I would like to evacuate the system before re-charging. I did some work on my compressor, and now my venturi vacuum pump is producing about -20 inHg, which means i'm evacuating about 2/3 of the air in the system. That's not great, but it'll have to do. I also bought another canister tap valve that will allow me to keep the service hose of my manifold evacuated while I switch to the refrigerant canisters.

Anyway, the venturi vacuum pump is running now while I'm typing this, and then I'm going to charge the system and see if it works.
 

·
Premium Member
2001 VDC/SC One of a Kind
Joined
·
14,318 Posts
Fixed! I found a sticky relay!

Thank you for all your posted comments. No matter how smart or clever you think you may be there is always someone out there better (in my case several)!
:19:

I got a little distracted by life's other problems, but luckily it hasn't been too hot out, and I haven't needed the AC. Now I'm back at it.

Okay, so the good news is that the vacuum holds overnight, so I probably don't have a significant leak. The bad news is that i'm not getting as much vacuum as I would like to evacuate the system before re-charging. I did some work on my compressor, and now my venturi vacuum pump is producing about -20 inHg, which means i'm evacuating about 2/3 of the air in the system. That's not great, but it'll have to do. I also bought another canister tap valve that will allow me to keep the service hose of my manifold evacuated while I switch to the refrigerant canisters.

Anyway, the venturi vacuum pump is running now while I'm typing this, and then I'm going to charge the system and see if it works.
Make sure you don't overcharge it.
 

·
Registered
1998 Subaru Legacy Outback
Joined
·
9 Posts
Discussion Starter #16
Well, I've got cold air blowing. A thermometer in front of the vent says it's 50 degrees. Now we'll just see if it holds.

I was really surprised how long it takes to charge the system. The 12 oz can said it could take 5 to 15 minutes to empty the can, and mine took the full 15 minutes on each of the two cans.

Cardoc, I was worried about overcharging it as well. The sticker says 19-22 oz., and I put in two 12 oz cans plus another 3 oz. can that had oil in it. I figured that some of this would be left in the manifold hoses, but I had no idea how much. How can you tell if it's over charged?

I was also thinking of topping off the refrigerant on another of my cars, but again, I don't know how to tell when it's full and to stop charging.
 

·
Premium Member
2001 VDC/SC One of a Kind
Joined
·
14,318 Posts
That should be right. You put the oil in first? Generally a manifold set retains about a 1/4 lb.

If its overcharged, the compressor will cycle fast on/off. Too low and the low side will never come down, compressor stays on longer and you wouldn't get cold air. If the temp is 50 out the vents at idle and it was warm out, above 80-85F, then it sounds like you hit it. At faster RPMs the temperature will drop more.
 

·
Registered
1998 Subaru Legacy Outback
Joined
·
9 Posts
Discussion Starter #18
Yes, I put the oil in first, and the compressor is not cycling on and off fast, so I think i'm good.

Thanks for all your help. :29:
 
1 - 20 of 23 Posts
Top