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-   -   Lower A/C temps by rigging cooling fan. (http://legacygt.com/forums/showthread.php?t=210278)

ZX2Fast 07-02-2013 07:25 AM

Lower A/C temps by rigging cooling fan.
 
I can tell when the cooling fans come one while using the A/C. The vent temp has to drop 10-15 degrees. If the fans would run the whole time the A/C is on, that would do a lot to keep the cabin cold.

Has anyone already done this? It seems it would be simple enough to find the wire that comes from the A/C switch on the controls and splice that to the cooling fan relay.

My only concern is that even after a new batter, new alternator, and big 3 upgrade is that my battery still drains at idle with the lights and A/C running. The belt tension is good and the belts are new so I'm out of ideas on that one.

Kennyfvholla 07-02-2013 08:45 AM

Both fans are already in all the time, at least at idle and lower speeds, while the A/C is on.

snederhiser 07-02-2013 10:21 AM

Hello;
First thing to do is blow-out the crap out of the radiator and condensor with a air blower so these can do their job. Also sounds like your battery and your alternator is crapping out. The stock unit should be putting out 80amps, get them tested. At idle with the A/C on your idle should be around 900 rpm. Forget the switch, Steven.

ZX2Fast 07-02-2013 06:11 PM

My fans cycle with the a/c compressor.

The a/c blows out cold air, as long as the fans are on. The condenser is clean but that doesn't matter if the fans don't run.

The battery and alternator are new and pass the test at Auto Zone. The idles is between 900-1000 rpm.

As long as the fans run, the a/c blows out really cold but they only run when the compressor is actually engaged. When the compressor cycles off, the fans turn off, then back on again when the compressor cycles on.

Kennyfvholla 07-02-2013 06:51 PM

Well... I jumped the fans to run all the time at one point. But, mind you, this is when my A/C wasn't working because I had no condenser (i.e. no Freon).So, with no Freon, the pressure sensor in the canister was unconnected. This is a safety that doesn't allow the compressor to engage when there is no/low Freon.

I unplugged it and connected the terminals on the plug with a short 10 gauge wire, and unplugged the relay that controls the compressor so it would never turn on but both fans would run all the time.

You can do the same wiring thing I did and not unplug the relay, but you will be running the A/C compressor 100% of the time. That... is a bad idea.

ZX2Fast 07-02-2013 08:19 PM

Not only a bad idea, but it wouldn't take long to freeze the whole system. I don't want the fans to run full-time, that would make fuel economy suffer and could lead to high carbon build-up inside the engine, long-term. I want the fans to run when the a/c system is being used, even if the compressor is cycled-off at the time. Since there is a switch on the HVAC control for the a/c and there is a relay for the fans, it can't be difficult to do this. I just didn't want to spend the time trying to find the related wire diagram is someone has already done so.

I just can't figure why Subaru would design the system like this. Maybe they knew that 80 amps really isn't enough for a car with all the electrical equipment this thing has.

Kennyfvholla 07-02-2013 08:50 PM

Sorry, I guess I should have been more specific. When jumped, both fans are only on 100% of the time that the A/C is switched on.

85 amps at 1,000 RPM is not too terrible actually (Factory alternators on my 98 LGT and my 99 OBL were rated at 85. And all ratings are at 1k RPM). My 86 Z28 had a 45 amp alternator and my 04 Accord V6-6 only has a 100 amp alternator and has a quite a few more electrics.. The problem with the Subaru is all of the grounds on anything electrical. They were bolted to painted surfaces. This is why people frequently do the "grounding mod" or clean up the factory grounds. The grounding mod involves using larger gauge wire. So, some systems will actually be able to pull more power and run as efficiently as possible.

snederhiser 07-02-2013 10:49 PM

Hello;
You could be a little low on refrigerant, just serviced a car with the same problem. Hook up the gauges and add half a can, more if needed. Steven.

ZX2Fast 07-03-2013 06:50 AM

Quote:

Originally Posted by Kennyfvholla (Post 4490705)
Sorry, I guess I should have been more specific. When jumped, both fans are only on 100% of the time that the A/C is switched on.

85 amps at 1,000 RPM is not too terrible actually (Factory alternators on my 98 LGT and my 99 OBL were rated at 85. And all ratings are at 1k RPM). My 86 Z28 had a 45 amp alternator and my 04 Accord V6-6 only has a 100 amp alternator and has a quite a few more electrics.. The problem with the Subaru is all of the grounds on anything electrical. They were bolted to painted surfaces. This is why people frequently do the "grounding mod" or clean up the factory grounds. The grounding mod involves using larger gauge wire. So, some systems will actually be able to pull more power and run as efficiently as possible.

You also said the compressor would be on 100% of the time if the relay was left in. I plan to go through the diagram to see what I can do about using that a/c button to ground the fan relay.

I have upgraded the wires, from the alternator to the battery is an additional 4 ga wire, from the battery to the starter is an additional 8 ga wire, from the battery to the body is an additional 8 ga wire, and from the battery to the engine then engine to body ground is an additional 4 ga wire. All contact points that needed it were cleaned with a Dremel disc.

Quote:

Originally Posted by snederhiser (Post 4490812)
Hello;
You could be a little low on refrigerant, just serviced a car with the same problem. Hook up the gauges and add half a can, more if needed. Steven.

While I appreciate the suggestions, if the refrigerant was low, the overall temp of the a/c would be low. The temp is fine as long as the fans are running.

I topped off the system when the weather first started turning warm. I have my own 30# tank of R-134 and a manifold gauge set. It only took little more than an ounce.

Kennyfvholla 07-03-2013 06:53 AM

Quote:

Originally Posted by ZX2Fast (Post 4490975)
You also said the compressor would be on 100% of the time if the relay was left in. I plan to go through the diagram to see what I can do about using that a/c button to ground the fan relay.

Yes, the relay I removed controls the compressor. Jumping the sensor will cause the compressor to run all the time. If the A/C system is itself is switch on, the fans will run 100% of that time regardless of that relay being there or not. That relay only controls the compressor. There are several for the system itself...

twisty 07-08-2013 07:41 AM

hell, i live in phx and dont have much issue with the car blowing warm air while the compressor is cycling. i never noticed the fans dont come on without the compressor, ill have to take a look tonite.

mnstrmech 07-08-2013 08:11 AM

the ONLY reason the a/c compressor is cycling is because its low, plain and simple. Have it PROFESSIONALLY evac/recharged and in wont cycle. Problem solved. NEVER trust the gauges, that doesnt tell you how much refrigerant is in the system.

twisty 07-08-2013 10:48 AM

cycling is relative. even a properly filled compressor will cycle, just not that often. when its low, you may see it cycle every few seconds or so. when its low enough, the low pressure cut off will engage and it wont cycle at all.

monkeyposeur 07-08-2013 08:38 PM

When I overcharged my system it would cycle on and off. When it was really hot it would shut off completely and I would just get hot air. Works great now that I had a pro do it. I would rather do all my own work but I won't touch the AC system since I don't have the proper tools/know how.

ZX2Fast 07-09-2013 07:06 AM

Quote:

Originally Posted by mnstrmech (Post 4495412)
the ONLY reason the a/c compressor is cycling is because its low, plain and simple. Have it PROFESSIONALLY evac/recharged and in wont cycle. Problem solved. NEVER trust the gauges, that doesnt tell you how much refrigerant is in the system.

Not that plain and simple. The system is supposed to cycle. If a properly filled system didn't cycle, it would freeze.

The problem isn't a cycling compressor, it is a cycling fan. When the compressor is running and the fan is running, I get Arctic Circle out of the vents. But, when the compressor first starts to cycle back on, the air gets warmer until the fans get up to speed. Not warm, but warmer. The kind of temp you get from a low system. It every other vehicle I've had contact with, the fans run full-time, even if the compressor is currently cycled-off at the moment.

An overfilled system will show higher than normal pressure on the high side (relative to outside temps) and this car shows the proper pressure on both sides of the system. I have my own gauges (plural, I can read high and low pressure) and 30# cylinder of R-134a. I've been filling a/c systems for years and this is the only Subaru I've done and the only car with cooling fans that don't run the entire time the a/c is on.


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