Drivebelt smokes when defogger is on...

[ratterrier]

Hi guys,

As I was driving my '96 Explorer in the rain yesterday, I turned on the front window defogger. Shortly after a great deal of smoke started pouring out of the hood. I stopped the engine and took a look under the hood. The smoke was from the drivebelt and seemed to be originating from the area of the air conditioner compressor pulley. After I let the truck cool down and turned off the defogger, I drove it safely home without incident.

I wasn't aware that the A/C would engage when the defogger goes on. I'm not sure what is exactly locking up, or what caused it, and I'm initially thinking that I may need a replacement compressor. According to my Haynes manual, I'll need to get a pro to discharge the refrigerant, but it looks like the disassembly may be handled by a backyard mechanic like myself. Has anyone experience this drivebelt problem and know what the cause may be, and if so what is your opinion of the mechanical work involved ??

Thanks as always,
Richard

 

[MyExpWork]

Yeah, sounds like your A/C pump is seized.

Mechanically, it should be simple to remove/replace the A/C compressor, ecspecially since its right on top. Its just a matter of removing a few bolts. The refrigerant should be removed by a pro if you don't want that stuff entering the atmosphere. That parts up to you.

But to replace the refrigerant will be expensive if you are using the old R-12 stuff. YOur a 96 so it could be the R-154 you can pick up at Wal-Mart and refill yourself.

 

[Glacier991]

I would agree that your compressor is likely siezed. Recharging a new one is not as simple as buying some 134 at Walmart and putting it in. Review the thread on here on "Recharging your A/C A -Z". ALso in the "useful Threads" there is a lengthy thread on AC. For now unplug the connector on the top of the compressor and you will be fine to drive it until you can get it replaced.

 

[kfkodiak]

The a/c compresser does kick on in defog. mode. It uses the system to dehumidify the incoming air, making it more effective at removing condensation.

 

[ratterrier]

Advice acknowledged, but....

Thanks Glacier991,

I noticed while going through any posts that may help that you are both a frequent and knowlegable contributor. Could you please explain to me what effect unplugging the top connector will have ?? I haven't driven the truck much lately, but it seems like it should be OK as long as I don't turn on the AC or defogger. Is there something that I am unaware of ??

Also, what might cause an AC cpmpressor to seize...is it common ?? I'm thinking about replacing it myself (and having a pro evacuate it first), because it doesn't seem like too much is involved according to my Haynes manual, but the instructions are very sparse. What is your opinion on the skill needed ??

Thanks,
Richard

I would agree that your compressor is likely siezed. Recharging a new one is not as simple as buying some 134 at Walmart and putting it in. Review the thread on here on "Recharging your A/C A -Z". ALso in the "useful Threads" there is a lengthy thread on AC. For now unplug the connector on the top of the compressor and you will be fine to drive it until you can get it replaced.

 

[A Wise Guy]

Could you please explain to me what effect unplugging the top connector will have ?? I haven't driven the truck much lately, but it seems like it should be OK as long as I don't turn on the AC or defogger. Is there something that I am unaware of ?? Also, what might cause an AC cpmpressor to seize...is it common ??
Thanks, Richard

When you unplug the electrical connections to the AC compressor you will not be able to accidentally turn it on while driving and the smoke from the other night won't be able to happen again.

AC compressors tend to seize from lack of use. Many newer vehicles turn the compressor on in just about every setting of the selector switch just to avoid the seize up problem. It used to be a more common problem then it is today but since they always run they don't seize as often.

 

[Glacier991]

The connector I mention is the electrical connector that supplies power to energize the clutch on the compressor when AC is called for (by turning ON A/C or defog mode). If you unplug it you can use your defroster, for the electrical signal will not get to the clutch, which is electrically energized. ( I sometimes will unplug this in brief periods in wintertime to spare myself the constant clicking of that clutch at cold temps - never for long though)

If you read the thread and links in them in the "useful threads" section, you can draw your own conclusions on doing your own A/C. Is it doable ? certainly.

Why do compressors sieze (and why do fools fall in love?). In general it is a failure of lubrication. (For the former anyway). There are several different general designs in compressors, each has advantages and disadvantages. Frankly the early FORD FX-10 (which was replaced by the FX-15) was not a terrific compressor lifespan wise. In A/C the refrigerant load carries the lubricant (sort of like a 2 cycle engine). Over time, leaks and innumerable other problems (moisture entering the system creating acid comes to mind) lead to a breakdown of lubricity and the compressor literally eats itself up from the inside out.... in the trade it is called the "Black Death". Good news is, you can easily replace the compressor. Bad news, usually the metal shavings, pieces of O-rings and crud contaminate everything. Luckily, the orifice tube has a screen on it, and it will often protect the evporator. Often as not a "black death" system will require a new compressor (duh) new accumulator, new condensor and replacement of the top line with the little muffler can on it. Everything else gets flushed until it runs clear. Because you have a 96, you have an R-134a system, and it has a high side overpressure vent on it. If you don't clean things out well enough, the orifice tube will plug up again after your rebuild and the over pressure vent will dump your refrigerant and oil overboard to protect from too high a pressure (I think it's set around 400 psi if I recall correctly.

ANyway go read the threads on AC in the Useful Threads forum portion. I'll be happy to answer any other questions I can for you.

 

[Glacier991]

I was composing my reply as "A Wise Guy" was answering your questions. He's right. But I want to clarify one thing, having to do with non-use. In the old days (pre 134a) Ford went to a system that cycled the AC sometimes when you might not think it would be needed - just to run the system on occasion. This was done to prevent the seals from becoming "leaky". Now what the exact reason was (seals taking a "set, lack of lubrication, etc) I am not sure, but THAT was the reason.

Along comes 134a. As refrigerants go, R-12 and R-22 (your home AC refrigerant probably) share a HUGE plus plus, oil dissolves in them readily and stays in the refrigerant. It's called "miscability" and they have it in spades. R-134a? NOT as good in carrying oil or keeping it in suspension. In the early days battles waged over WHICH oil (PAG or Ester) was best. Different manufacturers set their own standards. But it was necessary to run the system now and then to keep the oil from settling out in low places as I have been told. (possible auto urban legend)

With all that, A Wise Guy had a good point, but I am not sure I'd extend it so far as to say that lack of use is the actual culprit, just sometimes a precursor in 134 systems. Hope this helps avoid anyone thinking OMG I didn't use my household AC all winter, will it burn up ? (those compressors are also quite different, hermetically sealed with oil in them.....) I would also add one point about some of the newer blends - eg. duracool, autofrost, etc (not to re-raise the controversy in the main "converting to 134" thread in the useful threads forum.... blends have their own set of "miscability" problems. I'll leave it at that.

 

[ratterrier]

Thank you both, Glacier 991 and Wise Guy...

I looked through some of the thread postings before, but I'll do it some more with increased perserverance. I'll have to spend some time finding a decent shop in my area to do the evacuation (and cleaning), and will price parts. Hopefully I won't have incurred the "Black Death" and can just do the compressor. I'm starting to think a curse has been placed on my truck, as I also have a leaky head gasket which will need attention too (this will be left to experienced pros).

Thanks again for the help and offer of future assistance.

Richard

 

[ratterrier]

Hi again,

For now I think I may have to go the route that Glacier991 suggests and unplug the connector on top of the AC compressor. However, when I tried to disconnect it there was some resistance. Clumsy as I am I have broken things like this previously. Is there any special way to correctly unplug this wire, or do I need to use a tool to hold in a tab while removing it ??

Thanks,

Richard

 

[Glacier991]

The little "hook" on the side of the connector just needs to be pulled out gently while you wiggle the connect up and out. A small screwdriver is perfect for the job.