A/C Guru's

[fiction1990]

1995 explorer limited. I had a leak that took me a while to narrow down but I think I have finally found it( the accumulator). So I changed the accumulator and did not hav the system evac'd( stupid I know but time and money were a factor) I used the 2134 cans you get at autozone to charge the system and it seemed to charge fine didn't blow as cold as I would like but it would do do now. One of the lines was not pushed quite all the way on and was leaking so I lost all my r134 so I try and fill it but the compressor won't kick on ( before anyone jumps to conclusions the compressor is ok) so I tried to bypass the low pressure switch and still nothing. I tried jumping directly from battery to compressor and it works fine. I swap relays check fuses nothing makes it kickon. So I started looking at the wiring and found that I have juice through pin 85 on the relay and nothing else if I jump 85 to 87a clutch kicks on. I tried bypassing allsensors I can find and can't get it to engage the clutch. Does anyone have any ideas please its suppose to be getting hotter here and the truck is black.

 

[fiction1990]

if I push the relay in while the power is on the relay does click but nothing on the clutch

 

[budwich]

actually, what relay are you referring to???? The only relay in the AC compressor "powering circuit" is a "turn off" relay NOT a "turn on" relay... that is, if it operates, it turns off your compressor..... sssooooo it should not be "clicking".

Of course, you checked you fuses right?

 

[general x]

Curious, I know on bigger trucks (Like an older Kenworth) there is a small thermal switch in the A/C cooler box that regulates the on/off of the compressor clutch. As the cooler in the box cools the air, the metallic strip in the switch either breaks or completes the circuit and as it warms from the compressor no longer running it does the opposite, allowing the A/C clutch to not be running full time while keeping the incoming air cool. Couldn't tell you if the explorers use the same. Got a manual, and if so, does it have an A/C wiring diagram?

 

[fiction1990]

yes fuses are all good and the relay is the wac (i think ) its in the dist box and it has a wire that goes straight to the compressor ( no power, but if I jump power to it clutch engages) it also has a wire that goes to high pressure switch and one that goes to the low the low pressure switch and the last one is a power wire.. The only one that has power is the power wire which made me think the relay was bad but I tried swapping relays with the fuel oump relay and the ocm relay which are known good ones and still nothing

 

[budwich]

the circuit is "straight forward" as you have found / described. Measure for power at each point... ie. leaving the fuse, arriving at the low pressure switch, leaving the low pressure, arriving at the high pressure (WAC), leaving the high pressure, arriving at the relay (WOT), leaving the relay. Please do this as your previous description is "unclear" (at least to me)... as you say "only one that has power is the power wire"... IF that is true AND you don't have power "arriving" at the low pressure switch.... you have found your problem... a wiring issue between the fuse and switch.

 

[fiction1990]

sorry for being unclear... The only wire at the relay that has power is the pcm wire (pin 85 I believe) the other 3 that come from the relay donot have power.. They are the low pressure, high pressure, and power to the clutch.. All I had with me at the time of testing was a test light so I don't know how much power is coming from the pce.. I will have to look at the wiring schematic again. Is there power from the eatc to the relay somewhere?

 

[budwich]

now you are "in to it".... you didn't indicate in the first post that you have an EATC based system.... that's a whole different "kettle of fish" versus the "standard dial AC / heater" system.

Anyways, the main difference is that the EATC control module is providing "battery feed" to the low pressure switch at the "start of the chain". As suggested, do your measurements along the "chain" and you will readily identify your problem area.

 

[PerryH]

If you don't have power on pin 30 of the WOT relay your clutch will not engage.

The clutch circuit is as follows...

Fuse (#18 in the interior panel I think 15A), to

The EATC controller, the white/purple wire is the wire in, top left of the plug on the left of the EATC (as you are looking at it from the front of the EATC)

The solid purple wire is the wire out of the EATC.

Then to the low pressure switch,

Then to the high pressure switch,

Then to pin 30 on the WOT relay,

Then to pin 87 on the WOT relay (or 87A, I can't remember without the diagram in front of me),

Then to the clutch (and diode in parallel with the clutch solenoid).

I just fixed my own EATC problem. I had an intermittent 10 volts on pin 30 of the WOT relay. If I put a load on it (a trailer light bulb) the 10 volts would disappear. I traced the problem to the EATC controller.

I jumpered across the white purple/solid purple wire and got full voltage on pin 30 of the WOT relay. That narrowed the problem down to the EATC board. The local junkyard didn't have one so I took mine apart to look at it. There is a relay on the board and the solder joint on one of the relay pins was bad. There was evidence of heat/burning at the pin (the PCB was discolored). After resoldering that joint and plugging everything back up it worked like a charm. So if you have the same problem, don't give up on your old EATC board without checking the solder joints on that relay.

My relay was okay, but if it is bad the part number is (Ford number):
f5rf-14a640-ca
It is made my Omron and their part number is:
G8SN-UA-007115