Blower motor only blowing fuses...

I have a 1990 XJ 4.0 Pioneer AW4

This morning I turn on the AC and it comes on for maybe three or four seconds, and then shuts off. Heater doesn't come on either. So I pull into Shucks and check the fuse. Sure enough, it's blown. I replaced the 25amp fuse, turned the AC on; it works for about three seconds, and then blows the fuse again.

Any idea why this is going on?

Only thing different I have done is yesterday I wired in a fan switch to the orange wire going to the relay, and got the power for the switch from the fuse panel. While I was doing this, the top of my hand brushed against the small light bulb under the driver side dash. After I made contact it started to glow really bright. Then the "area" of the light started smoking pretty good. I undid the battery cable ASAP and removed the bulb.

No idea if all of this is just coincidence, or not.

Anyway, it is HOT over here, and need to get my AC fixed. Any ideas?

A '90? Why did you tap a power source for your mechanical fan switch? There's another thread going on this topic. All you need to do is tap the two wires from the sensor in the dricer's side radiator tank and run them to a toggle switch. The sensor is a switch, so the toggle just goes in parallel with the thermal switch.

If your modification resulted in smoke, it seems pretty obvious that it did something more than what you expected. It's clear to me that the first step in trouble shooting the problem would be to remove or disable your modification, and see if things revert to normal. If so, pull out your new wiring and wire the aux fan switch the way 5-90 described in the other thread. It sounds like your new "hot" wire is backfeeding something, but I can't visualize what.

If the temperature isn't to warm the compressor will kick off and back on as needed to cool your interior. My '88 has always done this when it's not to warm but will run all the time when it is hot!

Eagle, ok, then what are the exact wires I should be splicing into? Are they on the relay in front of the washer fluid tank? I spliced into the orange wire and ran a line back to the switch.

Here is the write up I went by: http://www.olypen.com/craigh/auxfan.htm

I unplugged the AC clutch fan switch, and it stopped blowing fuses, only now it wont blow cold air. Will I need to drain out the R12 to replace the switch? I untwisted it a bit, then it started spraying it at me.

Anyway the heater seems to work fine (blows hot air), but whenever I turn it on now it draws lots of volts (I can see the gauge fall). The AC switch was left unplugged. Could this be why?

Could my wiring job somehow of fried the switch? I had the AC on (while it was working, AFAIK, and hit the switch for the fan. I didnt notice if it stopped working or not at the time.

The smoke coming from wires was from entirely different ones. The wires that run to the small bulbs under the dash.


Would this be a good time to have my AC system flushed and to a R134 conversion? How complicated would this be to do?

Thanks for the help!

What do you think could be causing this? I

The purpose of a relay is to take the load off a switch that couldn't handle a higher current draw. The relay will have four wires, two that are lower amperage that activate the relay, and two with a higher amperage that are actually flowing through the relay when the contacts close. You may have tapped into the lower rated wires and might be drawing too much power through a circuit not designed to handle that much load and blowing the fuse.

90NHXJ said:

The purpose of a relay is to take the load off a switch that couldn't handle a higher current draw. The relay will have four wires, two that are lower amperage that activate the relay, and two with a higher amperage that are actually flowing through the relay when the contacts close. You may have tapped into the lower rated wires and might be drawing too much power through a circuit not designed to handle that much load and blowing the fuse.

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I'm pretty sure I got the right wire, at least according to this write up. Even though it happens with the switch shut OFF?

Thanks

90Pioneer said:

Eagle, ok, then what are the exact wires I should be splicing into? Are they on the relay in front of the washer fluid tank? I spliced into the orange wire and ran a line back to the switch.

Here is the write up I went by: http://www.olypen.com/craigh/auxfan.htm

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Craig normally knows what he's talking (writing) about, but I never understood why he wired his fan the way he describes, except that you'll note he said he wanted it hot at all times so he could leave the fan running with the engine off. Personally, I would not want that -- I know I'd go away and leave the fan running for a week -- or until the battery died.

The sensor for the fan is located in the driver's side radiator tank, about halfway down. It has two wires coming out of it. All you need to do is tap into both of those wires, and connect on to each side of your toggle switch. Your toggle switch is now in parallel with the thermal switch in the radiator.

I unplugged the AC clutch fan switch, and it stopped blowing fuses, only now it wont blow cold air. Will I need to drain out the R12 to replace the switch? I untwisted it a bit, then it started spraying it at me.

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Now that you mention this, I am reminded that a couple of years ago mine was blowing the same fuse. I found that one of the two wires that run along the top of the compressor, under the heater hoses, has chafed and was shorting against the compressor housing. Inspect those wires carefully.

The smoke coming from wires was from entirely different ones. The wires that run to the small bulbs under the dash.

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Don't have a clue how/why this would be related, unless it's because of where you tapped for the hot lead toy your aux fan switch. That's why I suggested first simply disconnecting your new circuit to put things back as they were, and see if that eliminates the problem. The timing suggests that the problem was caused by the aux fan wiring modification, but that may be a coincidence and they may actually be unrelated.

Would this be a good time to have my AC system flushed and to a R134 conversion? How complicated would this be to do?

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If your a/c is holding pressure and was blowing cold air before this problem started, there's no reason to convert to R-134a. The electrical system is unrelated to the gas system.

Thanks for the reply Eagle, it's appreciated. I do have just a couple more questions.. what color are the the wires by the radiator tank? I'm not very mechanically inclined, so I'm not exactly sure what/where this is. Perhaps it will become obvious once I am out there looking for it tomorrow.

I unplugged the switch I wired in from the fuse panel, but the AC still blows fuses. This is kind of leading me to believe they may be unrelated, but I may very where be wrong. I just don't know. I'll try check the two wires on the compresser tomorrow.

I tried replacing the AC clutch control switch, but when I went to unscrew it, the thing started spraying r12 at me. How can I go about replacing the switch without draining it? Or perhaps that switch is not even bad? That's why I asked about converting it, since 134 is a hell of a lot cheaper.

Thanks again for the help Eagle


I forgot to mention, the bulb connected to the smoking wires was entirely black after I removed it, so perhaps it was just the bulb smoking? Either way I don't think I'll be putting a new one in.

90Pioneer said:

I forgot to mention, the bulb connected to the smoking wires was entirely black after I removed it, so perhaps it was just the bulb smoking? Either way I don't think I'll be putting a new one in.

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by not putting in a new bulb is not going to fix your problem. sounds like you have it wired wrong or you have a short somewhere.

89xj said:

by not putting in a new bulb is not going to fix your problem. sounds like you have it wired wrong or you have a short somewhere.

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It's the factory wiring, and it seems to be fine since I removed the bulb.

OK, here's an update on my progress..

Today I tried the switch, and it wouldn't even work, but it used to before. I don't know why, but the only thing it did was blow a dome light fuse. Seemed to work yesterday and the day before, I don't know why or what happened.

Anyway I unplugged the power from the fuse box and tried the AC... still blew a fuse...
So then I snipped the wire I ran from the switch to the orange wire on the relay, and reconnected the originals as they were. Now the AC works great, and doesn't blow any fuses.

But, I am right back where I started... No aux fan switch. I have no idea where the radiator tank is, unless you're referring to the coolant resevoir (but that is on the passanger side)? But the relay with the orange wire I tapped into originally was right in front of the wiper fluid resevoir.

Which wires do I tap into? A picture would be great, or even a bit more detail on the location.

I have a white and black wire coming out of the fan, which plugs into a connector, then that connector runs back to the relay with the orange wire. Only those wires that run from the connector are black.

PLEASE someone help me with which wires I tap into.

Thanks!!