Air Condition Relay wire very hot

mangic

Hello,
Could use some help. I have a 91 westfalia. The wire that runs from the 50 amp fuse to the evaporator fan relay is very hot. The black wire on the same relay is also hot. The air condition works well but I'm concerned with the heat. I can't even hold the wire it's so hot. I temperarly replaced the 50amp fuse with a 40amp breaker for safety. Has anyone experienced such a thing?

Thanks,
Hector

Dogpilot · Posted: Tue Aug 12, 2008 12:18 pm Post subject:

Hector,

I cold be a few things, but I would start with two. First the actual fan speed switch gets burned over time and the contacts get covered with carbon. This increases the resistance in the system. The switch is cheap and easy to replace on the 91.

The other item is the fan bearings start to not be so bearing like as they age. If you can get to your fans. Spray so Tri-Flow or LPS 2 oil on both sides of the bearings. Lubing them up will halve the amp draw by the fans. Do not use WD40, it is not really a lubricant.
_________________
Geology with a Syncro rocks!
86 Syncro Westy AKA "The Bughunter"
98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G

mangic · Posted: Tue Aug 12, 2008 2:40 pm Post subject:

Thanks Dogpilot. I just replaced the fan switch and the temp switch. I'll try lubing the fan. Do you have a suggestion for getting to them without disasembling the entire cabinet?

Thanks again,
Hector

Dogpilot · Posted: Tue Aug 12, 2008 2:45 pm Post subject:

Those spray lubes have the skinny tube sprayers. THe problem is they are never long enough. Use two, connected by small tubing, like IV tubing or something equally small. If it isn't small enough heat the end and stretch it, it gets smaller. In my westy I can remove the front of the vents and open up the side access to the fans and work this extended tube system near the axels and spay the bejeezus out of them.

Also check for corrosion on the spade connectors at the resistor in the cabinet.
_________________
Geology with a Syncro rocks!
86 Syncro Westy AKA "The Bughunter"
98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G

mangic · Posted: Tue Aug 12, 2008 2:50 pm Post subject:

Cool will do. Is the resitor reachable by hand through the vent?

Thanks

Dogpilot · Posted: Tue Aug 12, 2008 2:57 pm Post subject:

Mine was right there, but it is an 86. Yours could be under the luggage rack for all I know. It would make sense that it is close to the fans. All you really need to do is reseat them, spades almost self clean when you do this.
_________________
Geology with a Syncro rocks!
86 Syncro Westy AKA "The Bughunter"
98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G

mangic · Posted: Tue Aug 12, 2008 3:11 pm Post subject:

Great. Will try it when I get home. Thanks for the advise.

Hector

maocg · Posted: Thu Aug 21, 2008 7:51 am Post subject:

Hector,

I have been fighting hot wires on my 91 Westy. I am told by my mechanic the Evap Fans are good and there are no shorts in the system. All leaks have been repaired, I have replaced many of the seals, new compressor, new condensor, new fan speed switch (up front) and it blows very cold air. I have had AC battles for three summers.

The wire coming from the Altenator gets very hot, the breaker gets very hot and the wires going to power the evaporator fans get very hot. At Fan speed 3 the fans are pulling 35.5 amps. I currently have a 40 amp breaker on it which will trip after 2-3 minutes at fan speed 4 again with very hot wires.

I am learning as I go and am working to help discover the solution to the hot wires with my dedicated mechanic. This site has been very educational and inspiring for me. Someday I might pick up the wrench!

Is my van a three season van?

Thanks,

Matt

mangic · Posted: Thu Aug 21, 2008 8:19 am Post subject:

Thanks Matt,
Yeah frustrating, mine also trips after a few minutes. The correct amperage is 50 but I'm afraid the wires will burn if I leave it at 50. My system has a new compressor and switch as well, I even tried changing the terminals. I'm thinking that even though my fan works that it may pulling too much amperage. I'm planning on doing some testing with a 12v motor that pulls less amps just to see if the wires still get hot. If that works I'll replace the fan motor.

Thanks,
Hector

maocg · Posted: Thu Aug 21, 2008 8:34 am Post subject:

Hector,

One thing that did drop the amps a little was cleaning the ground. Yeah 50 is correct however, I had a little incident with a band aid repair my former mechanic made after the 50 amp strip fuse blew at the end of the summer last year, two 25 amp fuses in parallel and it caught fire. Note I said former and I learned a thing or two.

Keep me posted on the fan motor. Would running a heavier gage wire reduce the amount of heat if all other systems are found to be sound?

Matt

Dogpilot · Posted: Thu Aug 21, 2008 9:45 am Post subject:

I have an extra fan I got at a junkyard while collecting vital spares. So last year, when this discussion was up I took it out and ran it with the amp meter hooked up. Simply lubing the bearings reduced the draw of the fan by half. With two fans in the system and the radiator, reducing the draw by half is quite significant.
_________________
Geology with a Syncro rocks!
86 Syncro Westy AKA "The Bughunter"
98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G

Alan Brase · Posted: Wed Sep 03, 2008 11:01 am Post subject:

Dogpilot · Posted: Wed Sep 03, 2008 1:05 pm Post subject:

Al,

Just for you, I went and re-did the test. Off the shelf the fan pulled 12 amps, single fan on my workbench. I used three test leads, to simulate larger wire gauge. Then it went through my Fluke 87. I then lubed the visible bearing with Tri-Flow® and pushed the tube down as far as I could through a large cooling opening in the side of the metal motor housing and did a healthy amount of lube that way. Let it sit and soak for a couple of minutes. Ran it again, dropped to 9.2 amps. Now I had lubed this fan before, but about 1.5 years ago, and very lightly, and I didn't try the hidden bearing flood technique.
_________________
Geology with a Syncro rocks!
86 Syncro Westy AKA "The Bughunter"
98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G

Alan Brase · Posted: Thu Sep 04, 2008 10:14 am Post subject:

Those blower motors, when in the front heater housing, typically burn out the 20 amp fuses and still run. Not WELL, mind you! So, you are confident that you are getting lube on the front, outside bearing under the fan hub?
thanks,
Al
_________________
Al Brase
Projects: 67 sunroof bug, 67 Porsche 912 Targa, 70 Westy
Dec 1955 Single Cab pickup WANT 15" BUS RIMS dated 8/55, thru 12/55
To New owners: 1969 doublecab, 1971 Dormobile
Vanagons:
80 P27 Westy JUL 1979, 3rd oldest known US
83 1.6TD Vanagon, 87 Wolfie Westy daily driver, swap meet home

tencentlife · Posted: Thu Sep 04, 2008 1:42 pm Post subject:

I know this is contrary to the rantings of a certain denizen of these parts, but in the handful of those motors I've disassembled, it's the tail bearing that wears the worst, by far. The one at the center of the fan wheel itself is nearer the center of gravity of the spinning mass, while the tail bearing (bushing) is what bears greater side forces due to the lengthened moment arm. So lubing both is good, if you can do it, but it's at least been my observation that the tail bearing gets the worst of it, so if you can only lube that one you're still doing a great deal of good.

I have a used fan I reconditioned which is destined to replace my front under-dash blower, if I ever get around to it. Meanwhile, I have a method of shooting some lube at the tail bearing on it, and once a year gets me thru the winter without noise. So the R&R may never happen!
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Please don't PM here, I will not reply.

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Alan Brase · Posted: Thu Sep 04, 2008 10:04 pm Post subject:

tencentlife · Posted: Fri Sep 05, 2008 7:46 am Post subject:

Well it's just what I've seen from, as I said, a pretty limited survey. The tail bushing is much more worn than the one at the fan end. It makes sense to me, and airflow could be a factor but I think the inertial imbalance is important. The fan and rotor as an assembly have their center of moment much closer to the fan bearing end; that means that torque reactions and vibrations will be transmitted more to the bearing farther away from the center of balance. Just a theory, but I'm sticking with it!

By the way, the denizen of these parts I was referring to hasn't commented on this thread. Yet.
_________________
Shop for unique Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/

Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

dameeser · Posted: Fri Apr 24, 2009 11:28 pm Post subject:

I have a problem with the relay connection side of the wire coming from the alternator getting hot only when i turn the ac unit on. Has anyone got any more information on this problem?

Dogpilot · Posted: Sat Apr 25, 2009 9:27 am Post subject:

You may want to replace the connectors on that wire. They can corrode under the crimp part making them very inefficient. It is a good place to start anyway.
_________________
Geology with a Syncro rocks!
86 Syncro Westy AKA "The Bughunter"
98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G


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