A/C Not Working - Ford Explorer Ranger Enthusiasts "Serious Explorations"®

pearsonbe · 06-20-2006, 10:16 AM

The A/C in my '91 is not working and I'd like to get some idea of common issues. The light comes on when the button is pushed, but I don't hear/feel the compressor engage. I've read a few of the A/C posts and my understanding is that that if the charge is low, the compressor will not cycle. Is this correct?

**Glacier991** · 06-20-2006, 04:06 PM

That is correct. There is a switch which porevents the compressor from coming on without adequate charge - thjis is because the refrigerant also carries the lubricant for the compressor. Without refrigerant a running compresser will self destruct in short order.

I'd have your syatem evacuated, and properly recharged, and leak tested.

pearsonbe · 06-20-2006, 04:08 PM

Thanks Glacier.

HardTech · 06-21-2006, 08:37 PM

Just recently had the pressure switch go south on me. It was easy to tell; I just pulled the plug on the accumulator and then stuck a paper clip from on side of the plug to the other to complete the circuit. The A/C compressor finely engaged at that point.

I then went to replace the part, $15 bucks later my A/C is back.

**Glacier991** · 06-21-2006, 08:44 PM

Certainly the low pressure cutout switch can and does go bad - as you have so well illustrated. BUT, a word of caution that may save someone $15-$20.

If your system has a low charge, such that the low pressure cutout will not allow the compressor to engage, AND if you jumper the wires like HardTech did... YOUR COMPRESSOR WILL RUN. Now if you then think - AHA! It was a bad switch, well... that is like shooting the messenger. Buy a new one and it still will not allow the compressor to run, and you cannot return it.

Check your system pressures first in this situation.... and ONLY after you know you have some decent charge - enough to make the system run (40PSI or so) should you even suspect the low pressure cutout.

Which... is why I recommended he have a shop check it... they might see right off if there was a sufficient charge.... most DIY'ers cannot. And the little gauges with the death kits are pretty worthless, especially in the hands of newbies (IMHO).

**BrooklynBay** · 06-22-2006, 01:25 AM

If your system is going to be completely evacuated (vacuumized), then this is a good time to replace the orifice tube. Those things do pick up a lot of stuff, and could get clogged. Take a look at Shamaal's orifice tubes in the picture below:

HardTech · 06-22-2006, 02:49 AM

Yes I can see where creating the circuit would cause some problems when it may be low. But one thing he did not comment on was when the last time it was working. I assumed it quit within the past few days and up till that point it was cold air and had been cold air.

My problem is that it would start and be fine for a good half hour then kick off, finely it just got to the point it didn’t come on. There’s really only 2 things that can cause it not to kick on if the clutch is still good. Not enough pressure or a bad switch. Last time I checked a switch is cheaper than figuring out the pressure unless you have the right tools. And I think its the optimistic approach to the problem. Because if there’s no pressure in the system, then well bigger problems exist. (I don’t mind throwing 20 bucks at car, its when its 50 or over I care. It’s just less scratch off’s I buy). Local I know its 50 bucks just to check if the system has something in it or not. Its 2 mins or less of work for 50 bucks.

Also you can try to make it turn on by creating a circuit like I said above. If the system is undercharged it should be fairly apparent. An undercharged system will not get cold, maybe cool but not cold. Also if you do this check to see if the top of the accumulator is getting cold. Normally if its low the bottom may get cold, but the top doesn’t

(Feel free to correct me if I am wrong, but its worked for me 3 out of 3 times for me. I don’t insist im an A/C master or even a novice, just things ive noticed in the cars that ive had the pleasure to toy with.)

As for the orifice tube pic... WTF happened. I replaced mine when my A/C cruded out, but even at 130k+ miles it looked just like the new one I put in it. It did not look like that... Got the story behind that one, did the unit burn up at one point of time or something?

**BrooklynBay** · 06-22-2006, 11:15 AM

In the thread about that tube, it seemed like he had a lot of metal shavings clogging up the system. If you have a continuity tester, you could see if the pressure switch is making contact, or not.

shamaal · 06-22-2006, 06:29 PM

It's actually a condition called "Black Death". If I understand it correctly, the teflon seals in certain models of compressor break down, melt and flow through the system. No metal shavings involved. When this happens the gunk gets caught in the condensor also and because it solidifies at ambient temperature cannot be flushed out. If you poke around some of the A/C component sites, they will void their warranty if a compressor/accumulator is replaced and the condensor isn't when black death occurs.

**BrooklynBay** · 06-22-2006, 07:31 PM

Shamaal, did you end up replacing a lot of parts on your system to clean all of this stuff out? How does it work now?

shamaal · 06-22-2006, 08:41 PM

I changed the compressor because the compressor had a slow leak leak, evidenced by an oil spray line under the hood. I got a kit, that consisted of the compressor, accumulator and orifice. The orifice results you can see above. I read in several places thet when tis occurs the condesor has to be replaced. If you look closely at the picture there is no evidence that the crud made it through the orifice into the output screen so I assumed the evaporator was fine. I also changed the hoses because there was a gash in the suction side and I did not know the muffler was hollow. The only thing not changed was the evaporator and the orifice line.
I overfilled the freon at first, evidenced by condensation on the suction hose, then took out too much. After adding a small amount (<4 oz) I hit the sweet spot. I'm guessing about 24 oz +/- 2 oz. The line into the evaporator feels cold and the line out feels cold. The trick was to wait a couple days before messing with it. If I did this stuff repeatedly I'd get an electronic sight gauge like Glacier991.
While driving at 45 mph:

Ambient = 92 deg
Vent = 52 deg
SWEET!!

I did notice that my compressor is on all the time while in the driveway. When driving it goes on and off. I suspect that the lack of air flow over the condensor while in the driveway raises the pressure in the system. That's my story and I'm sticking to it.
Thanks for asking

06-20-2006, 10:16 AM	#1
pearsonbe Wannabe Elite Explorer Maryland 91 XLT Join Date: Jan 2005 Posts: 28 Vehicle Specs	A/C Not Working The A/C in my '91 is not working and I'd like to get some idea of common issues. The light comes on when the button is pushed, but I don't hear/feel the compressor engage. I've read a few of the A/C posts and my understanding is that that if the charge is low, the compressor will not cycle. Is this correct?

06-22-2006, 01:25 AM	#6
BrooklynBay Aerostar Forum Moderator Brooklyn, NY 88 89 93 95 96 Aerostars Join Date: Nov 2005 Posts: 29,054 Vehicle Specs	If your system is going to be completely evacuated (vacuumized), then this is a good time to replace the orifice tube. Those things do pick up a lot of stuff, and could get clogged. Take a look at Shamaal's orifice tubes in the picture below: __________________ My list of useful threads. My photo gallery. My product reviews. My list of items for sale. Aerostar owners thread. Aerostar parts work in Explorers, Rangers, and Bronco II thread. History of the Aerostar thread. Aerostar Forum. New Members Forum.

06-22-2006, 11:15 AM	#8
BrooklynBay Aerostar Forum Moderator Brooklyn, NY 88 89 93 95 96 Aerostars Join Date: Nov 2005 Posts: 29,054 Vehicle Specs	In the thread about that tube, it seemed like he had a lot of metal shavings clogging up the system. If you have a continuity tester, you could see if the pressure switch is making contact, or not. __________________ My list of useful threads. My photo gallery. My product reviews. My list of items for sale. Aerostar owners thread. Aerostar parts work in Explorers, Rangers, and Bronco II thread. History of the Aerostar thread. Aerostar Forum. New Members Forum.

06-22-2006, 07:31 PM	#10
BrooklynBay Aerostar Forum Moderator Brooklyn, NY 88 89 93 95 96 Aerostars Join Date: Nov 2005 Posts: 29,054 Vehicle Specs	Shamaal, did you end up replacing a lot of parts on your system to clean all of this stuff out? How does it work now? __________________ My list of useful threads. My photo gallery. My product reviews. My list of items for sale. Aerostar owners thread. Aerostar parts work in Explorers, Rangers, and Bronco II thread. History of the Aerostar thread. Aerostar Forum. New Members Forum.

06-20-2006, 04:06 PM	#2
Glacier991 EF Tranny Guru Sacramento, CA 95827 1992 XLT Join Date: Feb 2003 Posts: 9,779 Vehicle Specs	That is correct. There is a switch which porevents the compressor from coming on without adequate charge - thjis is because the refrigerant also carries the lubricant for the compressor. Without refrigerant a running compresser will self destruct in short order. I'd have your syatem evacuated, and properly recharged, and leak tested.

06-20-2006, 04:08 PM	#3
pearsonbe Wannabe Elite Explorer Maryland 91 XLT Join Date: Jan 2005 Posts: 28 Vehicle Specs	Thanks Glacier.

06-21-2006, 08:37 PM	#4
HardTech Wannabe Elite Explorer Anna, Tx 95 XLT Join Date: Jul 2005 Posts: 198 Vehicle Specs	Just recently had the pressure switch go south on me. It was easy to tell; I just pulled the plug on the accumulator and then stuck a paper clip from on side of the plug to the other to complete the circuit. The A/C compressor finely engaged at that point. I then went to replace the part, $15 bucks later my A/C is back.

06-21-2006, 08:44 PM	#5
Glacier991 EF Tranny Guru Sacramento, CA 95827 1992 XLT Join Date: Feb 2003 Posts: 9,779 Vehicle Specs	Certainly the low pressure cutout switch can and does go bad - as you have so well illustrated. BUT, a word of caution that may save someone $15-$20. If your system has a low charge, such that the low pressure cutout will not allow the compressor to engage, AND if you jumper the wires like HardTech did... YOUR COMPRESSOR WILL RUN. Now if you then think - AHA! It was a bad switch, well... that is like shooting the messenger. Buy a new one and it still will not allow the compressor to run, and you cannot return it. Check your system pressures first in this situation.... and ONLY after you know you have some decent charge - enough to make the system run (40PSI or so) should you even suspect the low pressure cutout. Which... is why I recommended he have a shop check it... they might see right off if there was a sufficient charge.... most DIY'ers cannot. And the little gauges with the death kits are pretty worthless, especially in the hands of newbies (IMHO).

06-22-2006, 02:49 AM	#7
HardTech Wannabe Elite Explorer Anna, Tx 95 XLT Join Date: Jul 2005 Posts: 198 Vehicle Specs	Yes I can see where creating the circuit would cause some problems when it may be low. But one thing he did not comment on was when the last time it was working. I assumed it quit within the past few days and up till that point it was cold air and had been cold air. My problem is that it would start and be fine for a good half hour then kick off, finely it just got to the point it didn’t come on. There’s really only 2 things that can cause it not to kick on if the clutch is still good. Not enough pressure or a bad switch. Last time I checked a switch is cheaper than figuring out the pressure unless you have the right tools. And I think its the optimistic approach to the problem. Because if there’s no pressure in the system, then well bigger problems exist. (I don’t mind throwing 20 bucks at car, its when its 50 or over I care. It’s just less scratch off’s I buy). Local I know its 50 bucks just to check if the system has something in it or not. Its 2 mins or less of work for 50 bucks. Also you can try to make it turn on by creating a circuit like I said above. If the system is undercharged it should be fairly apparent. An undercharged system will not get cold, maybe cool but not cold. Also if you do this check to see if the top of the accumulator is getting cold. Normally if its low the bottom may get cold, but the top doesn’t (Feel free to correct me if I am wrong, but its worked for me 3 out of 3 times for me. I don’t insist im an A/C master or even a novice, just things ive noticed in the cars that ive had the pleasure to toy with.) As for the orifice tube pic... WTF happened. I replaced mine when my A/C cruded out, but even at 130k+ miles it looked just like the new one I put in it. It did not look like that... Got the story behind that one, did the unit burn up at one point of time or something?

06-22-2006, 06:29 PM	#9
shamaal Wannabe Elite Explorer Friensdwood, Texas 91 Mazda Navajo Join Date: Apr 2005 Posts: 1,307 Vehicle Specs	It's actually a condition called "Black Death". If I understand it correctly, the teflon seals in certain models of compressor break down, melt and flow through the system. No metal shavings involved. When this happens the gunk gets caught in the condensor also and because it solidifies at ambient temperature cannot be flushed out. If you poke around some of the A/C component sites, they will void their warranty if a compressor/accumulator is replaced and the condensor isn't when black death occurs.

06-22-2006, 08:41 PM	#11
shamaal Wannabe Elite Explorer Friensdwood, Texas 91 Mazda Navajo Join Date: Apr 2005 Posts: 1,307 Vehicle Specs	I changed the compressor because the compressor had a slow leak leak, evidenced by an oil spray line under the hood. I got a kit, that consisted of the compressor, accumulator and orifice. The orifice results you can see above. I read in several places thet when tis occurs the condesor has to be replaced. If you look closely at the picture there is no evidence that the crud made it through the orifice into the output screen so I assumed the evaporator was fine. I also changed the hoses because there was a gash in the suction side and I did not know the muffler was hollow. The only thing not changed was the evaporator and the orifice line. I overfilled the freon at first, evidenced by condensation on the suction hose, then took out too much. After adding a small amount (<4 oz) I hit the sweet spot. I'm guessing about 24 oz +/- 2 oz. The line into the evaporator feels cold and the line out feels cold. The trick was to wait a couple days before messing with it. If I did this stuff repeatedly I'd get an electronic sight gauge like Glacier991. While driving at 45 mph: Ambient = 92 deg Vent = 52 deg SWEET!! I did notice that my compressor is on all the time while in the driveway. When driving it goes on and off. I suspect that the lack of air flow over the condensor while in the driveway raises the pressure in the system. That's my story and I'm sticking to it. Thanks for asking