A/C Fuse Keeps Blowing

[mahleek87]

Hi Guys,

The A/C fuse in my 89 Van under the dash keeps blowing. I have already blown 3 of these 15a fuses. It all started yesterday. Within 20 minutes of driving with the a/c on the fuse blows.

About a week ago I finally replaced the fan motor on top of my a/c condenser but it worked fine for a week (without blowing any fuses) I dont know if these two events are related.

Where do I start?

[timsrv]

Blowing fuses can be aggravating. I'm guessing this is related to the condenser motor as the intervals suggest something that doesn't run all the time. You will need to check amp draw on this motor to know if it's within specified limits. If you don't already have one, you should get a meter capable of reading DC amps. Then use it to track down your problem. Tim

[mahleek87]

The blower motor is from Toyota. I got it fixed a week ago from my mechanic and I didn't start blowing fuses until yesterday. Meaning it worked fine for a week without blowing fuses.

I don't know anything about electronics but I do know the resistor was bad and my mechanic bypassed it to make it to make the fan spin.

i guess I'll try to have him look at it and report back.

[mahleek87]

I talked to my mechanic and he insisted that I order the resistor since we bypassed it. He is certain that is the issue.

Question is, are these resistors still available? And what is the part number if anyone has it. The resistor on the condenser.

[timsrv]

Yeah, that could be the issue. I don't know if it's still available or not, but it's Toyota Part #88648-87012

[mahleek87]

Ok so we replaced the resistor with a brandnew OEM one from Toyota. Didnt fix the problem. Still blowing the A/C fuse after about 15 minutes of driving or so.

Is it possible I could have picked up a bad condensor fan motor? Its an OEM from toyota.

Anything else I can check? My mechanic gave me a phone number of an electrition. He told me hes a little expensive but assured that he could trace the problem.

Dont really want to spend $ on this. I was thinking about disconnecting the fan motor and calling it a day and see if it blows anymore fuses. Because before I installed that it was fine and not blowing fuses. Ofcourse I didnt get great a/c when I was sitting in traffic but yeah.

[timsrv]

Make sure it's supposed to be a 15A fuse there. If it's rated for 15 then leave it 15, but if it calls for a 20 there you may have a solution. Seems a bit unlikely to be a bad motor, but it is possible. Disconnecting it is one way to troubleshoot. If it stops blowing fuses then it's time to check current draw to it. Tim

[mahleek87]

I have always put 15A fuses in there. Would it be the end of the world if I put a 20? My mechanic also noted that my blower motor is in its beginning stages of failure. Meaning sometimes you have to tap it to come on. He said he thinks it is possible that could be an issue to as to why the fuses may be blowing. I am going to disconnect the condenser fan motor today and see what happens.

[timsrv]

Your blower motors for the interior are on circuit breakers, so not likely these are creating the issue. Your fuse box cover & your owner's manual both give you maps of what fuses go where and what amperage they should be. Never replace a fuse with one of a larger value than what is called for. Fuses are there to protect wires. If your wires can only handle 15A & you force them to take 20A, it will not likely end well (don't do it). I would recommend a close inspection of the work your mechanic did. When things like this happen immediately after work was done, it usually isn't a coincidence. Perhaps you will see something obvious (like a pinched wire). Good luck. Tim

[mahleek87]

*** THE PLOT THICKENS ***


Disconnected the resistor from both connections at the bottom by the condensor to ensure the fan was no longer connected and now the fuse blows as soon as I touch the a/c button. Instead of before with the resistor connected and the condensor fan spinning it would blow after about 15 minutes.

I tried it two different ways. First I tried turning on the a/c in the front. Fuse blew right away.


Then I put a new fuse in and tried just turning the a/c on from the rear. Fuse blew right away.


Does this bring any new ideas? Perhaps we can definitely rule out the resistor, and condenser fan motor at this point.

[timsrv]

Something somewhere is shorted. You are going to need to test circuits & components for amp draw to chase it down. I would start out by testing the magnetic clutch & the idle-up VSV. I took a brief look at the AC schematics & have to admit they're a little intimidating, but it looks as though there might be some re-routing of power from the AC fuse to the front blower switch when the AC button/switch is engaged. So based on this I'm not so sure about my earlier statement about the blower circuit breakers handling all the load of the blowers at all times (so don't rule anything out). The easiest way to find the problem it is to get a DC amp clamp and use it to check everything for high current draw. To save yourself the expense & hassle of constantly blowing fuses (while troubleshooting), use a 15A self resetting circuit breaker to bridge the fuse terminals. Tracking it this way shouldn't be too difficult. Good luck. Tim

[mahleek87]

i know where the idle up VSV is, but where is the magnetic clutch? and how to test the magnetic clutch?

[timsrv]

The magnetic clutch is the what engages the pulley to the AC compressor. There's a wire going up to that area, check that for current draw.

[gushaman]

Does anyone have a picture of an a/c compressor showing the wiring and connector at the clutch? Or where is it and where should i look from?

[timsrv]

http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/IMG_3394_zps10ef6067.jpg

[gushaman]

Mine is definately missing the connector, and there is no ground screw either? Weird. Thanks tim

[mahleek87]

I talked to my other mechanic who is a Master Toyota Tech. I told him I wanted to bring the van in so he could check it out and see why it blows the a/c fuse as soon as I turn the A/C on. He was quick to say that it is a "bad compressor assembly" which as I understand is the compressor. He didnt look at it. He may be a little blunt but was pretty quick to rule everything out. My other mechanic is not sharp with electrical stuff so he refused to see it.

Do you guys think the whole compressor needs to be replaced? Or a part needs to be rebuilt?

[timsrv]

The coil (stater) for the AC magnetic clutch could be shorted, but that wouldn't require replacing the entire compressor. You could check that by unplugging the wire to the compressor and turning the AC switch on. If it still blows the fuse then it's not that. If it stops blowing the fuse, then perhaps you'll need another stater (for the magnetic clutch). Toyota part number for this is 88411-14050 & sells for around $160, but personally I'd pull one from a junkyard vehicle. Toyota used this same stater on early 80's Corollas, Celicas, Cressidas & trucks. 4 runners, & Land Cruisers used these from around 1984 - 1989. Tim

[mahleek87]

Thanks for the info Tim.

Yup the tech called me after I posted and explained to me exactly what you said that those go bad in the compressor. But then he said your better off just getting a new compressor or a reman one because who knows how worn out your original one could be...

Do you have a picture of the Stater?

[timsrv]

In the picture above, it's the part between the pulley and the compressor (with the 2 wires coming out of it). I got that compressor from rockauto for ~$150, but my compressor was froze-up (I needed it). If your system is charged and working (other than the short issue) and you're sure it's only a stater, then I wouldn't replace the entire compressor. Makes much more sense to replace just the stater. Replacing the compressor will require the system to be evacuated, the receiver/dryer replaced, and they system recharged (expensive). If it's just a bad stater, you can just unbolt from the front of the compressor and replace (no need to drain/process Freon). Everybody has their opinions, but seems that the professional mechanics always lean towards the most expensive ones :yes:. Tim

[mahleek87]

Hey Tim,

How is that compressor from Rock auto working so far? $150 for a compressor isnt bad at all especially if it comes with the Stater. Did you fill it up with r12?


Anyhow, I did some playing around with my van today and found out that now when I press the A/C button the fuse doesnt blow because the compressor doesnt even kick on anymore. The belt is on there fine and it is spinning nice. Anything else could have gone wrong?

[timsrv]

Compressor has been working fine. I'm using R-12 in all my vans (including this one). Last year while surfing craigslist I found a good deal on an AC machine (big one on wheels) that sucks out all the Freon and recycles it. Then after I'm done making repairs I use it (the machine) to pull a deep vacuum and pump the same Freon back in. It's got a precise scale built in so I can put back the exact amount required. Due to the cost of R-12, the machine has already payed for itself. The fact that it's fun to play with is an extra value (no extra charge) :thmbup:.

Your system has a pressure switch on it. If the pressure in the system is low (like you're out of Freon), the compressor will not engage. I don't know if that's what's going on, but you'll need to hook it up to a gauge set to see. If the fuse only blows when the compressor kicks on, then it probably is the stater. You can also do a continuity test on the stater to see if it's shorted. Tim

[mahleek87]

Hey Tim,

Can you send me a link to the compressor you bought on Rock Auto? I see a whole bunch of different ones with different pricing.

[timsrv]

This was about a year ago and I see it's gone now. The one I got is a Denso rebuild (I trust Denso as I've had good luck with them). Tim

[mahleek87]

In the picture above, it's the part between the pulley and the compressor (with the 2 wires coming out of it). I got that compressor from rockauto for ~$150, but my compressor was froze-up (I needed it). If your system is charged and working (other than the short issue) and you're sure it's only a stater, then I wouldn't replace the entire compressor. Makes much more sense to replace just the stater. Replacing the compressor will require the system to be evacuated, the receiver/dryer replaced, and they system recharged (expensive). If it's just a bad stater, you can just unbolt from the front of the compressor and replace (no need to drain/process Freon). Everybody has their opinions, but seems that the professional mechanics always lean towards the most expensive ones :yes:. Tim


Hey Tim,

I have already ordered the compressor clutch from ebay. Should be here in a few days. Just wondering how hard is it to change it? Any tips or tricks?

[timsrv]

There's a good step by step procedure in the service manual (AC section). You will need some snap ring pliers and some patience, but you should be able to handle it. Just make sure to put it all back on the way it came off. Tim