OE electric fan operation

Dent · **Joined:** Sat Aug 04, 2012 11:05 pm **Posts:** 275

Is the condenser fan supposed to run when the AC is on, or is it controlled by temp or pressure?

flash7210 · **Posted:** Sat Jun 18, 2016 12:21 pm

The electric fan is supposed to come on when the AC turns on.
It is usually activated by one of the pressure switches.
It will also turn on when engine temp hits 205.

Dent · **Joined:** Sat Aug 04, 2012 11:05 pm **Posts:** 275

Follow up. AC on, no electric fan. If I pull either the low speed relay or the high speed relay out of the fuse box, the fan comes on. ???

flash7210 · **Posted:** Sat Jun 18, 2016 12:46 pm

Yup.
When you pull either the low or high fan relay the fan will turn on LOW.

Is the AC turning on?
Is cold air blowing out the vents?

Dent · **Joined:** Sat Aug 04, 2012 11:05 pm **Posts:** 275

AC comes on, and blows cold, but it was blowing warm air yesterday on the way home, and it doesn't seem to be really cold when it is working. With AC on, the fan is not running. The high side pressure is at 225 psi with a 60° outside temp, which I thought was high.

flash7210 · **Posted:** Sat Jun 18, 2016 1:38 pm

Check the AC pressure switches.

papaindigo · **Posted:** Sat Jun 18, 2016 3:06 pm

My AC works just fine and I can affirmatively state the electric fan does NOT immediately come on when the vehicle is cranked up and the AC is on. FYI if you dig into the FSM there is a table that shows ideal AC air temp in recirculate mode at various outside ambient temps; good indicator of proper AC charge.

I suspect you have a bad pressure switch and/or the AC "freon" charge is low. Unless you are an AC person best take it to a good local AC shop; nothing special about the CRD AC system although parts (ex. compressor) may be different than gasser. Diagnosis and repair should be straight forward.

69Hcode · **Posted:** Fri Oct 07, 2016 11:55 pm

Did you ever figure this out? Just put in a condenser and fan on my friends jeep.
Same thing. Pull either fan relay and the fan comes on. With both relays the fan stops.

mass-hole · **Posted:** Tue Oct 11, 2016 12:00 pm

69Hcode wrote:

Did you ever figure this out? Just put in a condenser and fan on my friends jeep.
Same thing. Pull either fan relay and the fan comes on. With both relays the fan stops.

Mine wont run for about the first 30 seconds after I turn on the AC when parked and possibly longer if I am moving.

The ECM directly triggers both relays, which share a common fuse and power from the battery so its a fairly uncomplicated setup. Maybe check to make sure the wires from the ECU are ok?

JDaPP · **Posted:** Sun Feb 12, 2017 8:51 pm

My electric fan does not turn on with a/c on. A/c still blows cold. I am in San Diego/is not that hot but pretty sure it didn't blow this summer when it was hot either. I am basing that off electric fan used to run for a little bit after shutdown but hasn't done that in a long time. Just getting around to this because I was chasing suspension issues + work.

CRD doesn't run hot (have Hayden fan). Changed out fan this summer while doing the head gasket work. Works with pulling relays. Tried pulling low pressure switch and putting it back and switching fuses. No change.

My thought is to change relays and fuses first and then pressure switch? Where is a good place to get the relays/fuses (anything I need to ask for in particular)? Also how hard is it to switch out the pressure switch? Anyone happen to know part #? Thanks in advance.

WWDiesel · **Posted:** Sun Feb 12, 2017 11:19 pm

JDaPP wrote:

My electric fan does not turn on with a/c on. A/c still blows cold. I am in San Diego/is not that hot but pretty sure it didn't blow this summer when it was hot either. I am basing that off electric fan used to run for a little bit after shutdown but hasn't done that in a long time. Just getting around to this because I was chasing suspension issues + work.
CRD doesn't run hot (have Hayden fan). Changed out fan this summer while doing the head gasket work. Works with pulling relays. Tried pulling low pressure switch and putting it back and switching fuses. No change.
My thought is to change relays and fuses first and then pressure switch? Where is a good place to get the relays/fuses (anything I need to ask for in particular)? Also how hard is it to switch out the pressure switch? Anyone happen to know part #? Thanks in advance.

Part No.s, you can Google them:
AC High Pressure Switch – 04897617AA
AC Low Pressure Switch -- 04897612AB

From the FSM:
The A/C high pressure switch controls both A/C compressor clutch engagement/disengagement, and electric cooling fan operation when equipped with the 2.8L diesel engine.
The A/C high pressure switch controls the electric cooling fan operation by monitoring refrigerant line pressures. When the A/C discharge line pressure rises above 1900 to 2200 kPa (280 to 320 psi) the fan will turn on. The cooling fan will turn off when the A/C discharge line pressure drops to 1600 kPa (235 psi). The A/C high pressure switch contacts open when the A/C discharge line pressure rises above 3100 to 3375 kPa (450 to 490 psi). The A/C high pressure switch contacts close when the A/C discharge line pressure drops to 1860 to 2275 kPa (270 to 330 psi).
See Page no.s 8W-42-6 & 8W-42-7 in the FSM Wiring diagrams
:SOMBRERO:

JDaPP · **Posted:** Mon Feb 13, 2017 9:43 pm

Thanks!

JDaPP · **Posted:** Sun Jul 09, 2017 7:27 pm

Still haven't gotten to this, am I correct in assuming that swapping out the pressure switch will drive the a/c system needing to be recharged?

mass-hole · **Posted:** Sun Jul 09, 2017 7:49 pm

Did you ever try pulling one of the fan relays to see if it comes on at all?

Sent from my iPhone using Tapatalk

JDaPP · **Posted:** Sun Jul 09, 2017 9:17 pm

Yes, pulling the relays makes it work, which is why I am thinking pressure switch or needs a recharge. If changing the switch drives a recharge I will do them at the same time. Thanks.

Dent · **Joined:** Sat Aug 04, 2012 11:05 pm **Posts:** 275

I'm pretty sure my original problem with my AC getting warm after longer trips was due to a failed fan clutch combined with enough heat generated by the transmission cooler to make the AC not work so well. It went away with a new fan clutch, and now it's back again with another failed fan clutch.

Billybob · **Posted:** Mon Jul 10, 2017 2:29 am

JDaPP wrote:

Yes, pulling the relays makes it work, which is why I am thinking pressure switch or needs a recharge. If changing the switch drives a recharge I will do them at the same time. Thanks.

You can replace the switch without having to discharge the refrigerant...seals off automatically. :wink:

JDaPP · **Posted:** Mon Jul 10, 2017 6:34 pm

Perfect thanks. I will give that a try first.

jrsavoie · **Posted:** Sun Jul 12, 2020 9:36 am

What does it take to change the fan?

Do you have to pull the bumper cover?

OE electric fan operation

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