AC electrical question
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 102
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
Shotgun the low pressure switch and see what happens to the AC system.
The system will not discharge when removing the switch - it has a Schrader valve in the accumulator fitting.
See if you can get one from a junk yard.
The system will not discharge when removing the switch - it has a Schrader valve in the accumulator fitting.
See if you can get one from a junk yard.
Thread Starter
CF Veteran
Joined: May 2012
Posts: 1,209
Likes: 5
From: Puyallup wa
Year: 1999
Model: Cherokee
Engine: 4.5L Stroker
So Maybe the low pressure switch is bad ?
I can take one off my other Cherokee but they are cheap enough I don't mind buying a new one
I can take one off my other Cherokee but they are cheap enough I don't mind buying a new one
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 102
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
Thread Starter
CF Veteran
Joined: May 2012
Posts: 1,209
Likes: 5
From: Puyallup wa
Year: 1999
Model: Cherokee
Engine: 4.5L Stroker
Replaced ac low pressure switch and ac kicked right on. Fan still won't so I'll have to check the relay and go from there.
Thanks CCKen for you help and knowledge
Thanks CCKen for you help and knowledge
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 102
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
Glad that AC portion is fixed.
Study the above wiring diagrams and compare to the fan bypass switch you installed to see if there's any possibility that your wiring has somehow gone south and screwed up the fan circuit.
CF Veteran
Joined: May 2012
Posts: 7,965
Likes: 964
From: Lost in the wilds of Virginia
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
You'll do better starting a new thread. Zombies aren't well received on most forums.
Newbie
Joined: Sep 2023
Posts: 1
Likes: 0
2002 grand cherokee laredo, ac pressure switch?
On my 02 Grand Cherokee, it has a 4 pin cavity so which holes do I use to put in the paperclip to jump it. My ac clutch is not engaging. Where the connector plugs in, it is the 3 prong but I don't know which holes to use with the paperclip to see if the ac clutch will engage.
Try jumping the Low Pressure Cycling Switch connector on top of the AC Accumulator. The switch cycles the clutch and fan based upon pressure in the system. The switch contacts are normally open and when the switch senses pressure in the system the contacts will close. The High Pressure Cutoff Switch (by the compressor) is wired in series with the Low , Pressure switch. The contacts in this switch are normally closed and open when the system pressure is too high. Both switches must be functional for the AC system to operate.
Remove the connector from the Low Pressure switch and jump the two pin cavities using a small paper clip (see pic). Select AC on the Mode Selector. Start the engine. The clutch should engage and the fan should run.
If not, leave the jumper in the Low Pressure switch and remove the connector from the High Pressure switch and jump it. See if it works.
Get back with results.
Low Pressure Cycling Switch connector jumped:
Attachment 308689
Location of the High Pressure Cutoff Switch:
Attachment 308690
Remove the connector from the Low Pressure switch and jump the two pin cavities using a small paper clip (see pic). Select AC on the Mode Selector. Start the engine. The clutch should engage and the fan should run.
If not, leave the jumper in the Low Pressure switch and remove the connector from the High Pressure switch and jump it. See if it works.
Get back with results.
Low Pressure Cycling Switch connector jumped:
Attachment 308689
Location of the High Pressure Cutoff Switch:
Attachment 308690
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