I've searched this and a couple other sites and haven't found any info on the problem I'm having. My 1994 Cherokee XJ is throwing an obd1 code 33. My AC compressor and blower motor are not working at all. Nothing happens when I turn them on. However, if I run a jumper wire to them they both start working but only with jumper wire. I'm A pretty good mechanic but when it comes to electrical work I know how to start fires and get shocked and that's about the jest of it.
Also, if anyone knows if my Jeep has a low pressure switch and where it's located I might pay money for that correct answer.
Any help with these matters are greatly appreciated.

 

Are you jumping direct to the coil on the AC clutch? Does the compressor kick on and deliver cold air? Are you using a separate jumper for the blower? The AC and blower work independently. Do you mean the electric auxiliary fan?

The low pressure switch is mounted to the receiver/drier.

 

On my receiver/dryer there's the high pressure switch. I've traced the hi and low lines looking for it but haven't found one yet. And yes, using separate jumper wires for compressor and blower motor. And no, it's not the engine cooling blower motor.
It has been a VERY frustrating situation, to say the least. And this summer in Southwest Georgia has been BRUTAL, with no relief in sight.

 

Did you try to replace the relay? Maybe the problem is exactly wha the code is reporting?

 

Yes, I've checked the relay and replaced it, just for ****s and giggles. Still nothing working. I'm gonna try checking the wiring to the from pdc for a short or open circuit and replace the relay socket. Everybody, cross your fingers an say a Prayer for my Jeep and me.

 

Just wanted to say thanx to you guys for trying to help me. This A/C troubleshooting is hard if you lack any real training/knowledge about the systems.

 

I would recommend you purchase a dc test light, this is one of the best tools for troubleshooting wiring problems. Hook the alligator clip to ground and then put it on the lead for the coil terminal and verify you have power when the ac is switched on. Also verify you have power at the relay. This should be a larger wire , possibly red at the relay. If you don't have power there you will never turn on your ac, even if the relay is working.

 

After seeing a mechanic buddy he said my ac has an expansion valve and no low pressure switch. Which is why the switch on the receiver/dryer is not the low pressure switch, where everyone says that's where it is located. The compressor clutch has a piece that is broken. Which is probly why it doesn't engage. Blower motor doesn't come on unless you us jumper wire. Blower resistor is pretty much shot. Nowhere near 12 volts reading on it. 0.2 ohms - 2.6 ohms. Guess I need either a new compressor or clutch kit and resistor. Any takers for this adventure? .

 

Your system has a low pressure switch and an expansion valve.
The switch on your receiver dryer is a low pressure switch.
Your system also has a thermocouple switch in the air box that senses the temp of the evaporator. Your computer uses it to power the AC clutch relay.

Your blower should run on high if the resistor is shot.
Check your blower speed switch in the dash.
Check all your fuses with a properly grounded test light.

Jeff

 

I've checked all fuses, checked the control switch (nothing melted on this new one). I work at advance auto parts and whenever I looked up the low pressure switch it gives me a switch with 2 male blades and the "switch" that's located on the receiver/dryer is a small connector with female ends. Two completely different parts. Also, the wiring to the blower motor has power to both wires, - and +. I know it's not supposed to be that way. And since it runs perfectly with a jumper wire I think I might just straight wire it to a toggle switch. This has been the hardest, most aggravating crap I've ever tried repairing on this Jeep in 28, yes that's right, 28 years. I bought it brand new in April 1994.

 

Look up one for a 1995 or a 1994 with r134a
94 was a change over year.

 

What he said. The R12 one has the bladed switch. The R-134a has the "socket".

The Jeep part number for the R-134a is 4796072. It is LOW-PRESSURE cut off.

https://www.moparpartsgiant.com/part...f~4796072.html

 

Well, the info sticker in the engine compartment says it an R134a system. I'm beginning to think this XJ is a "Frankenstein" model, you know all different parts that were thrown in it because they worked.