AC inop

[Dirtykurty]

96 EB with automatic climate controls.
I've replaced the blend door, AC compressor, all O rings, canister and freon. If I connect 12V to the compressor it'll engage the clutch but there's no power to the plug, it has recommended amount of freon according to the sticker. I've checked continuity at the low pressure switch and the switch is closed or engaged but still no power to the compressor plug at all. All fuses are good, even replaced the relay for good measure. Also have 12V going to the relay and through the fuse.

What other electrical connections should I check?
Is there a high limit switch? If so where?

 

[rathrbcruisin]

get a set of gauges, you need to see what's going on. it's all about temperatures and pressure. also check these out: http://www.therangerstation.com/Magazine/June04/tech.htm

http://www.therangerstation.com/tech_library/Resurrecting_Your_Ford_Ranger_Air_Conditioning.shtml

 

[colintrax]

I believe there's a high limit switch, but I can't promise you that. Might wanna check auto parts store websites, safe bet if rockauto.com sells a high switch for your engine/year then you have one.

 

[Dirtykurty]

This is all electrical issue. Clutch engages when hooked straight to battery, I've bipassed both high and low pressure switch connections, replaced the relay (found new was bad) so swapped with one from fuel pump relay, all fuses are good and of correct capacity. Gauges won't tell me anything if the compressor doesn't work. I'm an or conditioning tech tech by trade so I've got gauges and tools, but cars a whole different animal. Is there another fuse/ relay box that I'm missing? I've got the one at the door jam and one under the hood.

It's a 5.0 96 awd with auto climate control.

 

[Big Z]

Since it's automatic climate control, you may have a thermostatic switch. The compressor might use the cabin air temp sensor or maybe it has a separate switch with a stinger going into the evaporator. If not, and there is an a/c button (not savvy with auto climate control...) see if there's power to it. When all the proper sensors are closed, the switch should have access to power to complete the circuit to the relay.

 

[Big Z]

And just to clarify, when you're bypassing the high & low pressure switches, are you using jumper wires to short between the 2 terminals on the harness side of both connectors?

 

[Dirtykurty]

That could be a cause. If anything it's located inside the controller. And yes,bypassed at the harness. I'm a certified ac technician but for homes, not cars. Thinking might replace controller from a few junkyard bitz. Grab about 5 of them if I have to.

 

[Big Z]

You might want to consider getting your 609 cert to cover your own rear.. you can do it online for about $20-30. Your 608 type 1/2/3 doesn't cover MVAC systems.

 

[SoHK_alumni]

Also, the PCM is an in-series switch with the high and low pressure switches.

The PCM will open the control circuit under wide open throttle and possibly during very high engine temp conditions.

At the 42 pin connector above the intake. Pin 30 pink/yellow wire and Pin 37 dk green/orange wire are for the WOT A/C cut off.

 

[Dirtykurty]

Big z, I've got 608 universal. It covers everything.

Sohk_alumni, what you're saying is that wot connection may be faulted somehow in either the pcm or the wiring itself could be disconnected or loose. I will check that out tonight after work. Right now I have it Jimmy rigged to work, 20 amp fuse and a separate switch going from ignition switch to the compressor clutch. Not my greatest moment or most liked idea bypassing the oem safety controls but it'll work for now.

Thanks for the advice guys,

 

[bobflood]

EATC has a relay on the circuit board that provides 12V to the compressor. Test for 12V at the input to the first place you can access it - I think the low pressure switch input - with a test light, NOT a meter. Meter can mislead you as it may provide a 12V reading but not enough current to operate the compressor. There are solder joints that hold the relay on the board that go bad.

At that point, you have two choices. Replacement EATC control units are commonly available on-line for about $100. Or you can remove the unit, disassemble it, and resolder the joints. The relay is a small black box on the circuit board. I did this a couple of years ago and it has been fine ever since. Good luck.

 

[Dirtykurty]

Bob flood, that eatc is the controller in the cabin, correct?

 

[bobflood]

Bob flood, that eatc is the controller in the cabin, correct?

That's right.

 

[Dirtykurty]

Awesome. This is most likely the culprit. I should have 12v going through the low and high side, low if it's connected to the switch or bypassed. I'll start messing with it today. Hopefully get this right

 

[Dirtykurty]

FIXED IT. Thanks for help guys! The relay on the eatc was disconnected from the solder point. Soldered it back, running like a champ! Bobflood,you're a genius!

 

[bobflood]

Wish I could claim genius, but it's the forum in total that is genius. I got this fix on this forum a couple of years ago; couldn't find the original post so I had to paraphrase it for you. Glad it worked!!

 

[Dirtykurty]

For the entire forums then thank you to all for the help in the past, present and future.