Dakota Durango Forum banner

1 - 20 of 24 Posts

·
Registered
Joined
·
56 Posts
Discussion Starter #1 (Edited)
I just replaced my compressor clutch assembly.
When I provide 12v directly to the clutch it engages.
It is not getting 12v.
I replaced my heater core so had to evacuate AC.
I put back together, installed new clutch as old one had short and pulled vacuum. I then charged and no clutch engagement.
I paper clipped the low pressure switch by firewall and no clutch.
Any help / advice on next steps is much appreciated.

Just checked again.

Getting 12v to the high pressure switch (switch on compressor), the compressor switch is showing a closed circuit. Plug high pressure back in and check low pressure switch. No 12v to the low pressure switch. The low pressure switch is showing closed circuit.

Any thoughts on why no 12v to the low pressure switch if the high pressure switch is getting 12v and is a closed circuit?

My 20a horn AC compressor clutch fuse is good.

Thanks,
Joel
 

·
Registered
Joined
·
1,505 Posts
Alright. I don't have a wiring diagram for your Durango but my Dakota is similar.

First, is your blower motor working on all speeds?

Dodge used some "tricks" in wiring up the pressure switches. They are between ground and the PCM, not 12 volts.

The HVAC blower motor relay is used to provide a "high" signal to the PCM when the a/c is OFF. When you turn the dash knob to select a/c, it provides a ground that:
1. It provides a ground for the blower motor relay.
2. It causes the PCM a/c input select to go "low."
3. It provides the ground path for the high and low pressure switches causing the PCM a/c switch sense to go "low."

In other words, you should not have 12 volts to either switch. You do have a/c selected?

You might try running a jumper from the low pressure switch to ground and see if the clutch engages.

The a/c clutch relay uses two fuses. One is for the coil side, the other is for the clutch itself.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #5
Yes blower motor working at all speeds.
Yes I had switched to AC Max, also tried defrost.
I checked the ac fuse on side of dash, the one that I was blowing with the bad coil. It also runs the horn, horn works fine, where before if I plugged in the clutch the fuse would blow.
Not certain on just how I'd jump the low side pressure switch to ground?
Not sure I understand the part about no 12v to switches. Do they not complete a 12v curcuit, ultimately to the clutch?
Or is it all through the computer?
Thank you very much,
Joel
 

·
Registered
Joined
·
56 Posts
Discussion Starter #6
AndPDan, was reading another of your posts:
It would be easier with the wiring diagrams. Is this on your 2000?

What do you mean you have power on both legs of the wires going to the compressor?

One side should be hot (dark blue with black tracer), fed by fuse #4 , 20 amp in the junction block with the other side (black) being ground. You should see 12v across it and if you do, the clutch should engage. It is run by a relay in the PDC. The relay is controlled by the PCM. There is a fuse, #7 , 10 amp, for the relay.

For the high/low pressure cutout switches, they are in series. Power is supplied via fuse D on the fuse/relay block under the dash. This feeds the "blower motor relay" located in the glovebox, the other lead passes through the high and low cutout switches and is switched to ground by the PCM.

All 3 fuses need to be good.

You'll only read power on the cutout switch sides if the ignition is on. Pull the connector and you should see 12v at the high pressure switch (light green with white tracer). If you do you've checked the fuse (D). Reconnect that connector and pull the low pressure switch connector. Do you still have 12v? If so, then you're not in a n overpressure (unlikely) situation. Ohm out the low pressure switch? If it's open you're low on freon.

Try that and see what happens. "

I get the 12v at the high pressure switch (one at compressor), I get continuity on high pressure switch, when plugged in I don't get 12v at low pressure switch. I do have continuity on low pressure switch (one at firewall).



Joel
 

·
Registered
Joined
·
1,505 Posts
Yes on my '00.

The PCM runs the clutch. The pressure switches just provide inputs to the PCM. They do not control the clutch.

The fuses/wiring colors are different on a Durango. As in the other post you should see 12 volts on the high and low pressure switches - IF the HVAC control is OFF. IF it's on, as I said in post #4 it will complete a path to ground (if the ground is good).

Have you tried jumping the high pressure switch?
 

·
Registered
Joined
·
56 Posts
Discussion Starter #8
I just checked again.
This time with the defrost on.

When I have the low pressure switch connected I get 12v at the high pressure switch plug.
When I have the low pressure switch unplugged I get nothing at the high pressure switch plug.
I get nothing at the low pressure switch plug either way.

Both the low pressure and high pressure switches have continuity which would mean to me I have enough charge that it should work.

I swapped out the AC relay with another of the same in the box under the hood and no difference.

Thanks for the help.
Not sure what to check next?

I've jumped both the high and low and nothing, which is not a surprise as I've got continuity at each switch, your other post said to check for continuity which frankly is not something I thought immediately of my self, that is a really good trick to quickly rule the switches in or out.

For what it is worth, I pulled the dash to do the heater core, maybe I did not hook something back up correctly? Maybe that is why you asked about the various fan speeds?

Again, thank you for the help.

I thought I'd plop in the new clutch and be off and running. Go figure.
 

·
Moderator
Joined
·
9,487 Posts
If you have ground at the green/white wire on the high pressure switch, then it has nothing to do with anything in the dash. Assuming Fuse 7 is good (check to see if your rear wiper works), there's a cycling switch wired between the high and low pressure switches. It's on the side of the expansion valve. It has two dark blue wires (one with a yellow stripe, one with a white) and a red wire with a green stripe. Jump the two blue wires (outer pins) together and the compressor should kick on.

 

·
Registered
Joined
·
56 Posts
Discussion Starter #10
Taz I jumped the two blue wires and the compressor kicked on.
Thank you.

Does this mean I need a new cycling switch?

I'm glad to have narrowed it down.

Funny, I just replaced the gasket (figure eight) on the expansion valve and thought nothing of the electrical switch there.

Just what does it do?

The diagram is greatly appreciated!!

Thank you again,
Joel
 

·
Moderator
Joined
·
9,487 Posts
Yeah the switch is shot. Basically it keeps the evaporator from getting so cold that it freezes up.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #12
Thanks, do I need the entire expansion valve or just switch, any idea where to find one? I've been searching net with little to no luck.
All the ones I see (expansion valves) have no wired switch.
Thank you,
Joel
 

·
Registered
1988 Dodge Dakota LWB RC 3.9V6 3 speed auto
Joined
·
1,481 Posts

·
Moderator
Joined
·
9,487 Posts
RockAuto shows them, but you should be careful and make sure you pick up the LOW pressure switch (they list the HIGH side and LOW side switches in the same category - Refrigerant Pressure Switch)

http://www.rockauto.com/catalog/raframecatalog.php?carcode=1361843&parttype=4656

With the numbers there, you can check and see if they're available locally too.

RwP
Way to read, dipshit. He needs the CYCLING/TEMPERATURE switch, not a pressure switch. :slap:

Joel - Unfortunately the cycling switch seems to have been discontinued by Mopar and there is no aftermarket. Alldata doesn't even have a part number listed. In looking quickly I've seen references to people who were able to use a 'universal' switch, but nothing in depth.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #15
Thanks guys
I will search around
By jumping the compressor will run continuously unless pressure switches kick in which could result in freezing correct? I am assuming the switch is not something I can fix correct?
Joel
 

·
Registered
Joined
·
1,505 Posts
You can't fix the switch, no.

Bypass it. The Dakota doesn't use it but the rest of the system is wired the same.

Diagram attached.
 

Attachments

·
Registered
Joined
·
56 Posts
Discussion Starter #17
Will do
I am not he at the moment
I will hook up my gauges so I can properly complete the charge
Thanks guys
Joel
 

·
Moderator
Joined
·
9,487 Posts
durangos have a large enough cabin that the air will never really get cool enough that the evaporator will freeze on a 'warm' day. what you have to be careful of is when you're using the defogger and it's cool/wet out. thats when it'll freeze.

and you can't charge by gauges. gauges only tell you if the system is operating properly, not if the charge is low or high - thats why those diy kits with the can and the fire extinguisher style low/ok/high low-side gauges are so aggravatingly worthless. you have to charge by weight. the dual coil durango system is generally 40 or 44oz. there's a blue sticker under the hood that will tell you.

in a shop it's done with a bulk tank on a scale, but with 12oz cans you have to divide the total charge by 12 - so for an empty system you shoot in 3 whole cans and then you'll have to guesstimate a quarter can.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #19
Much appreciated
I got two cans in before I realized something wAs wrong as compressor was not kicking in

I am tempted to evacuate pull vacuum and start over again.

I guess it can't hurt to add the other can and see what temp I get

I also want to add some oil as I lost a bit when I pulled the hvac box doing the heater core

What is the risk of freezing?
What will I break?

I hope others find this post as helpful as I have. Tough to find all this detail in one spot.

Joel
 

·
Moderator
Joined
·
9,487 Posts
-- shift keys on my laptop work intermittently, bear with me on parentheses and question marks, lol --

ok did you replace the evaporator/ did you lose ALL the oil out of the old one/

if not, then don't add oil. it only holds two ounces, and you have to put it directly back in. you could also use an oil charge, but that is 2oz of oil and 2 oz of r134 - and it can end up slugging in the compressor or condenser before it makes its way back to the evaporator.

if you properly evacuated the system before you put the first two cans in - meaning pulling it down to 29 inches for 30-45 minutes - then you don't need to start over. just shoot in the third can.

freezing isnt going to break anything, it just blocks the airflow. once it freezes you'll have to turn it off and wait for it to thaw.
 
1 - 20 of 24 Posts
Top