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91 Ford Explorer A/C issues

nitris

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Whats up guys,

Im new to the forum (as far as being registered) but I have used you guys info to fix a lot of things on my truck. Here's the issue that had me to sign up as I can't seem to fix the problem I am having. So I bought this truck for work and the A/C isn't working. It was a mess actually. I replaced the compressor, high pressure hose, accumulator, pressure switch, fuse and WOT relay but the darn thing still won't engage,the system has been flushed and is holding pressure very well, A/C light comes on in dash but nothing, I was told there is also an A/C clutch relay but I don't know where it is, as I tested the NEW non remanufactured compressor and it engages. Do anyone know where this mystery relay is? any pics of it? any help would be greatly appreciated.

Thanks Again!
:exporange
 


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arco777

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Look at the fuse center near the passenger side inner fender. It may be underneath the box.
 




nitris

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Look at the fuse center near the passenger side inner fender. It may be underneath the box.

the WOT cutout relay was there and I already replaced it, but I heard there was a clutch relay as well somewhere... I just don't know where.
 




shucker1

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If you have the owners manual look in the fuse section. My 98 owners manual list them all. Fuses and relays.
 




nitris

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If you have the owners manual look in the fuse section. My 98 owners manual list them all. Fuses and relays.

thanks ill try that, they actually had that when they sold it to me. The truck was such an awesome catch... $1500 with only 98000 miles.....
 




nitris

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UPDATE I just tested the wire leads at the pressure switch for power while the car was running on max A/C to find a reading of zero, even after I switched out the WOT cut out relay.... any idea what this may be?
 




shucker1

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Could be a bad fuse that powers the A\C clutch circuit. Or the coil in the relay itself is burned out.

Others may know more, but the current should travel from the battery positive to the fuse then to the dash switch out to the relay coil then on to the pressure switch on the accumulator your were talking about. From there back to the PCM where it gets ground.

When the clutch is told to engage the PCM need to know this so it can ramp the idle. Somewhere along the line your WOT switch should be in the mix so it can cut off the A\C during WOT.

Could be the A\C control switch in the dash itself having a burned \ loose contact.

You just have to follow the little electrons to see where they stop.
 




nitris

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Could be a bad fuse that powers the A\C clutch circuit. Or the coil in the relay itself is burned out.

Others may know more, but the current should travel from the battery positive to the fuse then to the dash switch out to the relay coil then on to the pressure switch on the accumulator your were talking about. From there back to the PCM where it gets ground.

When the clutch is told to engage the PCM need to know this so it can ramp the idle. Somewhere along the line your WOT switch should be in the mix so it can cut off the A\C during WOT.

Could be the A\C control switch in the dash itself having a burned \ loose contact.

You just have to follow the little electrons to see where they stop.


this is a tuff one, checked the fuse box in car and getting 14.6v while a/c is engaged, i have a new WOT relay... maybe its bad or the connections there are bad, how do i jump the relay to test if its bad? also where is the power and ground on the WOT relay?
 




shucker1

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Most of the automotive relays I've seen have the pin layout stamped on the bottom of the relay or on the side of the case.

It will tell you what pin does what. Hopefully you understand basic electrical symbols, if you do it will be easy.

If I'm not mistaken one of the older threads on this site there was a really good link to electrical wiring diagrams for almost every Explorer up to about 2000.
 




nitris

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Most of the automotive relays I've seen have the pin layout stamped on the bottom of the relay or on the side of the case.

It will tell you what pin does what. Hopefully you understand basic electrical symbols, if you do it will be easy.

If I'm not mistaken one of the older threads on this site there was a really good link to electrical wiring diagrams for almost every Explorer up to about 2000.

Fortunately I do... got some good old basic electronics and electricity certification from at&t.... the factory one I pulled didn't have a pin out.... the relay on the passenger side firewall does... but they are two different types of relays with two types of pin outs as well; hence why I didn't try to jump it yet... I'll do a search for those diagrams
 












nitris

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anybody know where the A/C wiring schematics can be found? i've searched with no luck
 




shucker1

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Basic electronics. You have a volt meter.

Let' s think here. So we start with the relay itself.

I have 5 pins, Common, N.O. N.C. and I need 2 to drive the coil.

So if I ring them all out and draw me a map I should have at least some resistance, like 200 Ohms, across the coil pins if the coil is good.

Next I should have almost no resistance across Common and N.C. and an open circuit across Common and N.O.

I can find common very easily from the relay socket. With the key off I should have a positive 12 volts back to ground on at least 1 pin.

You have to just sit and think through the problem. There is always an answer.

I have some work related reports to run down tonight. If I get extra time I'll try and hunt that link down.
 




shucker1

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Nitris,
 




shucker1

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nitris

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nitris

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shucker1

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Post #3 in the string has the correct link and the log in.
 


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nitris

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UPDATE ok so i re pulled the WOT relay and tested it to find no power there with the car off... I also noticed the replacement relay had one prong longer than the old factory relay, and also on the socket there is no wire in the area of the relay where the factory had the shorter prong...

the socket
ilOe34.jpg

old relay left new relay right
AUrGzT.jpg
 




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