96 Explorer Limited AC problem

[johnwartjr]

Greetings

Ya'alls helped me work through my spring shackle problem, so I'm empowered to try and fix this issue myself. This is my wife's daily driver and our kid hauler, so having no A/C in late May / Early June is a bit of a pain. I've got a pile of parts that I was just getting ready to install on my 95 Supercoupe, and then this reared its ugly head, so I had to come back to the Explorer.

96 Explorer Limited
135k miles
A/C was cycling the compressor about a year ago, so I added a part can of recharge from Walmart, the kind with the gauge on the can that has low, correct and warning. It went from 'low' to 'correct' and worked for the rest of the season.

A few weeks ago, I checked it and it was right at the low and correct line, so I added a bit more.

On the way home from a road trip on a very hot day this past weekend, it stopped blowing cold. Got home and checked under the hood, and the compressor wasn't cycling like it was low, but I figured it could be too low to cycle. Read in my service manual about it a bit, and tackled the next morning. When the engine was cool, the compressor started up just fine, put the gauge from the can of refrigerant on, and it had a sufficient charge.

A couple hours later, after it got hot, the compressor stopped working. When I say stopped working, I mean the clutch didn't engage and turn the compressor.

I know from reading a few threads here using the search function, it's necessary to have a complete set of gauge manifolds to get an accurate pressure reading - so perhaps the reading from the gauge is useless.

What I've done so far to troubleshoot:

-Turned 3/8 bolt in the center of the clutch. It rotates fine both directions
-Checked A/C voltage at the connector on top of the compressor for the clutch. It reads 11.1 VAC
-Temporarily shorted out the pressure switch on top of the evaporator core with a paper clip. It made no difference.

I've read a number of threads here and am not sure what steps to take next. I could procure a set of gauges, but there is an associated expense with that step - would be better off exhausting other troubleshooting steps before then, even if time consuming.

Any feedback/suggestions are appreciated.

Thanks!

 

[johnwartjr]

Ended up taking the wife's truck into a shop, because I am unable to troubleshoot further and have been working so many hours.

They worked on it, and said the levels are fine - the system is actually full.

However, the in-dash control unit was testing faulty.

It started working again while they were working on it. So, they tried to find a part for us, and Ford no longer makes this part. The best used part they could find was $280.

Something tells me, I can do better than that at a local pull-a-part, and I see one on eBay for $50 buy it now.

Has anyone ever heard of this part failing before? Is that common? This is the digital control unit as it's in a limited.

 

[Herbie 5.0]

mine has failed. it also depends on the color. they make diffrent color housings.pull yours before you order. i got one form the u pull it yard and i got the wrong color. so now im on the hunt again and got an a/c control that wont work on my explorer. hope that helps and saves you time

 

[johnwartjr]

To bring this thread back from the grave, I've replaced the control module with a 'tested good' one from a scrap yard.

Still doesn't work.

Tested levels again, the system is full and the high and low sides are at the correct pressure readings.

What's the next logical step? The compressor isn't seized.

 

[johnwartjr]

Finally solved this.

I took the 'old' control unit apart, and examined the PCB under magnification and found a burnt solder joint on a relay on the PCB.

I tried to reflow the solder, but the pin on the relay was burnt and would not take solder, even with flux. I carefully sanded the pin with a fiberglass sanding pin to expose fresh metal, and resoldered it.

After resoldering it, I reinstalled the first control module.

Nothing

After cursing up a storm, I got a jumper wire, and shorted the pressure switch. I'd done this before, but figured it can't hurt to try it again!

The compressor engaged and it started blowing cool air. The level was a little bit low, so I grabbed a can of 134 and a new pressure switch, installed the switch, and put some refrigerant into it.

Blows nice and cold now!

So, I'm at a loss. Don't want to put in the 'other' control module to see if it is indeed bad. I guess I could have had 2 failures the entire time and just not realized it.

 

[noremarks]

Just wanted to give a thanks to johnwartjr I too had no 12v at both pressure switches. so obviously no clutch engaged on the compressor. I re-soldered the pin on the relay and was back in business. Thanks