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Unread 07-18-2013, 02:50 PM   #1
exhdo1
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A/C issue after replacing electric fan

My son off roads his 2001 Grand Cherokee from time to time and he was having an issue with mud caking up around the electric fan. We removed the electric fan with it's housing frame and replaced it with a mechanical unit. Now he finds the A/C won't operate. I'm thinking there may be a sensor that does not see a fan in the system so it won't let the A/C engage. Before I start trouble shooting maybe someone here that has done the swap may have some info they can pass on. It's a 4.0, 4WD, auto trans.

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Unread 07-18-2013, 11:11 PM   #2
cykaaro
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What else was removed? anything? If it's just the fan, shouldn't make a difference and possibly just a coincidence. If the fan relay was taken out, maybe a possibility it's causing an issue. Typically though the electric fan should be left in, and a mechanical added to it. This is part of the towing package that was available that is typically seen on the V8's. I'm not sure how well the mechanical fan by itself is for cooling.

My XJ had both. Things got too warm, or the AC was on, the electric fan would come on automatically as the mechanical just wasn't enough by itself with the AC on, or in offroad realm of things, the transmission fluid was getting far to hard, which in turn heats the rad not having it cooling enough and the temp of the engine slowly start to climb in to overheating territory. Also always had an override on the electric so once stopped with engine off, could continue to cool everything by the electric fan.
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Unread 07-19-2013, 12:16 AM   #3
CopperDeer
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^ exactly. The PCM controls A/C compressor clutch activation, it won't know whether or not the fan is plugged in but it can detect if the relay isn't plugged in or functioning (this should throw a DTC for the relay, even if it isn't immediate). I don't think the relay being disconnected or faulty affects it allowing the A/C clutch to engage, though. Sounds like something else got disconnected accidentally or there is some damaged wiring.
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Unread 07-19-2013, 12:35 AM   #4
cykaaro
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The connector on my fan was my issue. Without it on and AC blowing it started to overheat, but AC did work. Can't speak for the relay, but you'd think the AC would still run. Just worry about overheating the engine is all.
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Unread 07-20-2013, 09:09 AM   #5
exhdo1
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Quote:
Originally Posted by CopperDeer View Post
^ exactly. The PCM controls A/C compressor clutch activation, it won't know whether or not the fan is plugged in but it can detect if the relay isn't plugged in or functioning (this should throw a DTC for the relay, even if it isn't immediate). I don't think the relay being disconnected or faulty affects it allowing the A/C clutch to engage, though. Sounds like something else got disconnected accidentally or there is some damaged wiring.
I think there may be an issue with the fan control relay. Everything else seems to check out. I'm not getting a code. I'm getting 12.5 volts at the connector to the fan. I tried plugging the fan back in, but it don't turn on when I call for AC or defrost. I bench tested the fan and it works fine. I'll try to test to see what kind of amperage I'm getting at the fan wire connector. I don't have a complete electrical wiring diagram for that Jeep. Just a haynes manual. The haynes manual does not show what part the fan control relays plays as far as the AC is conncerned.
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Unread 07-20-2013, 11:31 AM   #6
CopperDeer
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The PCM controls the fan relay signal itself taking into account these inputs: Engine coolant temperature • Ambient temperature from the body controller • Vehicle speed • Transmission oil temperature • A/C switch position (A/C request). If you're getting voltage at the fan connector, that means the fan relay is sending power to the fan. Testing the amp draw of the fan motor would be a good idea as well as amperage at the connector. There still may be a problem with the relay, it's common for them to get burned out by the fan even though the fan's current draw is fused.
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Unread 07-23-2013, 04:11 PM   #7
exhdo1
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Replaced the fan control relay today and put the electric fan back in. Brought engine up to temp and the electric fan kicked in, so the old relay was no good. Still no A/C. My son took it over to the shop. They evacuated the AC system, put a vacuum on it and recharged, still no A/C. I'm getting voltage at the cutoff switches, all the fuses check out but the compressor clutch will not engage. We did replace the PCM over a year ago and everything was working fine. I hope it's not another issue with the PCM.
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