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-   -   Air Conditioner 1997 Grand Cherokee not blowing (http://www.jeepforum.com/forum/f13/air-conditioner-1997-grand-cherokee-not-blowing-1543586/)

teddysmith1952 07-01-2013 01:09 PM

Air Conditioner 1997 Grand Cherokee not blowing
 
Hi all,

Well here's the issue I had today. Have had a tiny leak somewhere in the A/C system for several years. Every early summer I add one can of 134a freon to the system and that does the job until next year. Today I hooked up the can and gauge and as usual, it was down to about 20 psi (with engine running) before charging. I started the Jeep, turned the A/C and fan to high and proceeded to charge the system. It took the freon about 5 minutes to empty and the pressure on the low side went up to about 50 psi which is normal. I did notice that during the process the compressor would go on and off every 10 seconds or so and I don't recall if this has happened in the past. So I complete the charging and unhook the can/gauge. I go into the jeep and lo and behold the fan is not blowing air and there is no hint of cold air coming from the vents. Puzzled as heck!

Any suggestions on what just occurred would be greatly appreciated. Many thanks.

Oldfrog 07-01-2013 01:12 PM

Bang on the dash under the radio with your hand . If it still doesnt blow, check fuses. If fuse is good, it's probably the resistor.

coralman 07-01-2013 01:18 PM

If the fan wasn't running when you charged it then you have probaly overcharged the system. If it had been running before then you may have iced up the evaporator with a low charge to the point no air could pass through. Run system on fan only and verify the fan is actually running. The evaporator could have reached the point it is pretty clogged with gunk as ZJ's do .

dellis 07-01-2013 01:21 PM

When you say the fan is not blowing and no cold air, I'm assuming there is a typo somewhere (and you are saying the inside fan is blowing, but just not blowing cold air). Your charging experience seems normal ... except that's a long time to empty a can into a low system. But let me ask two questions:

(1) When the compressor was engaging, you were seeing the pressure on the low side drop from 50 to what? If it was 30-35, then you probably have enough refrigerant. If it was dropping to 20-25, then the compressor is detecting a low pressure situation and shutting off ... you would simply need to add another can of refrigerant.

(2) Now, assuming that #1 isn't your problem ... well ... I know this may come across like a computer help desk saying "do you have it plugged in", but was your temperature dial turned to hot? :)

teddysmith1952 07-01-2013 01:48 PM

Thanks for the replies and sorry for any confusion I created with my post.

Ok then. I started the jeep just prior to charging the A/C system. I turned the A/c to high and turned the fan to high as well. The fan was blowing air like crazy as usual and the air coming out was just moderately cold. The reading I was getting on my gauge while connected to the low side port was about 20psi when the compressor was engaged. When the compressor disengaged, the pressure was rising (as is should) towards the 60 psi zone but about then the A/C would engage again and it would start to drop. As the can emptied while going through this engage/disengage drill. the pressure while engaged, rose and steadied at about 50 psi when the can of freon was empty.

I can't answer when the fan stopped blowing during this whole process, only that it wasn't blowing when I completed the charging and went inside to test the degree of cold I was getting. The fan will not blow period now, when on A/C, heat or fan only. I did rap on the dash below the radio with no change. I'll go through the fuses to see if one blew. I also let the jeep sit for 30 minutes in case something had froze but still no fan. I'ts about 100 degrees here.

Thanks for your help all.

Oldfrog 07-01-2013 02:01 PM

Ok....now I understand. So it WAS blowing for a while, at least.
I dont place a lot of faith in those walmart gauges that come with the cans. It's possible that it froze up, but, depending upon the ambient temp. But I've never seen it. ( doesnt mean it cant occur) Let it sit, check fuse...and get back with us.

teddysmith1952 07-01-2013 02:27 PM

Just checked the fuses and they are ok. My wife just chimed in with a juicy tid bit I wish I knew earlier. She said the fan had been turning itself off and on (while in the on position) for a couple of week now when the A/C was on. I wonder if this event points to a specific problem. Thanks again.

dellis 07-01-2013 03:05 PM

Quote:

Originally Posted by teddysmith1952 (Post 15628940)
Just checked the fuses and they are ok. My wife just chimed in with a juicy tid bit I wish I knew earlier. She said the fan had been turning itself off and on (while in the on position) for a couple of week now when the A/C was on. I wonder if this event points to a specific problem. Thanks again.

Intermittant sounds like a fan motor going bad or an electrical connection problem (ground or voltage wires). However, it could be a couple of other things. On the circuit that controls the fan, there is also (a) a resistor block and (b) a blower-on relay (or the blower motor relay on some models).

(a) The "high" setting on your fan bypasses the resistor block, so it is pretty easy to test that (the resistor block is bad if it works on "high" but has problems on other speed settings).

(b) Test for voltage on the output of the blower motor relay ... or listen for it clicking on. The blower-on relay is located inside of your AC Heater Control Module OR on the side of the blower motor (I'm not sure which version you have). See images below. The electrical schematic shows the relay inside the control module, and the diagram shows the design version that has the relay on the side of the blower. You will have one of these two designs.

http://www.orangehound.com/misc/Jeep%20AC%20Circuit.gif

http://www.orangehound.com/misc/Jeep...20Assembly.gif

Oldfrog 07-01-2013 03:20 PM

This might NOT be your issue....and again...it might be :
Last year my fan didnt work at all sometimes. Mainly on High....but from time to time it just turned off. I'd slap the dash under the air controls and it would come back on, so one night I decided to find the culprit by taking the air control panel out. ( partially). I jiggled the connections ( mainly vacuum lines) and pushed them back up on the controls tighter.

It's never stopped working ever since.

dw2gtx 07-01-2013 08:49 PM

Fan motor problem
 
Just my 2 cents I had a similar problem with my 97 zj. Turned out to be a faulty connection in the electrical connector under the glove box. Check that.

teddysmith1952 07-02-2013 12:45 PM

Thanks for all the help and suggestions.

I don't know if this is a good thing or a bad thing but just to complicate matters I started the Jeep up this morning to pull it in the garage to start my troubleshooting. The blower fan worked like new!!! I was going to pull the glove box out and start checking electrical connections and by process of elimination work my way to removing and checking the blower if necessary. Having a working blower is going to make this impossible. I'm sure it will keep quitting but I wonder when..lol. I wonder if it has something to do with the engine/inside temperature?

Oldfrog 07-06-2013 08:19 PM

If it's an "iffy" electrical contact that's the problem, certainly... the ambient temps will affect it. I'd check behind the control panel first..and make sure it's all tight back there.

dellis 07-07-2013 06:36 AM

Quote:

Originally Posted by teddysmith1952 (Post 15632737)
Thanks for all the help and suggestions.

I don't know if this is a good thing or a bad thing but just to complicate matters I started the Jeep up this morning to pull it in the garage to start my troubleshooting. The blower fan worked like new!!!

That's a bad thing. Intermittent problems are nearly impossible to diagnose while the component is actually working.

Quote:

Originally Posted by teddysmith1952 (Post 15632737)
I wonder if it has something to do with the engine/inside temperature?

Perhaps, but it doesn't matter - intermittent is intermittent, regardless of the environment that causes the failure. Did you check the items I noted above?

coralman 07-07-2013 06:37 AM

Sounds like a crispy fried fan connector to me.

coralman 07-07-2013 06:50 AM

I might have missed it when you joined dellis, but welcome to the forum. Looks like you are pretty sharp on the electrical end of zj's.


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