A/C Blower Cutting Out

[VEGASXJ]

'94 XJ, 4.0, auto... When the engine is under a load, like pulling the motorcycle trailer climbing a hill, the air conditioning
blower shuts off. I can't find any evidence of a vacuum leak. I don't know what else would cause this. I hope someone can help me.
Thanks everybody.

 

[XJ Samo]

Check the water proof wire connection as well as the thermal fan switch which is located under the lower radiator hose connection on the radiator. I had a similar problem and found loose wire connection plus a failing thermal switch to be the problem. Good luck let me know if that does not work I have a freind who owns a jeep only shop, not dealer.

 

[slowrider]

Some vehicles will shut off the AC if your coolant temp is high. I don't know if it's the same kind of problem but it may be a vaccume leak, I'm having a similar problem on my 87 MJ that doesn't have AC and I know that if you have a big vaccume leak the fan defaults to the defrost setting. If you listen closely the fan may still be running but the vents are rerouting the air. Just a thought, I'm trying to figure it out myself, if I do I'll post it hear.

 

[hellabad]

Check the vacuum reservoir up behind the bumper on the passenger side. Because it is not under the hood, you will probably hear the vacuum leak. When you say that the A/C defaults to blowing out of the defroster vents, that is the clue.

 

[ErikL]

i have a similar problem.... my blower stops blowing if i am doing around 80 on the freeway with my AC on..... as soon as i slow down alittle it starts blowing again.... you can hear it running, it just stops blowing.....its not coming out anywhere, its wierd

 

[Cliff]

So how do you track down / test your system for vacum leaks i have this exact problem.

 

[seanman]

I also have this problem on both of my Cherokees 88 and 99. I thought the 88 was because it's a modified POS. But the 99 is the wifes and she doesn't allow me near it. Under load the air is deflected to the Defrost.

Sean

 

[old_man]

The computer can sense the load on the engine via several of the sensors. It will cut off the AC temporarily if it thinks it will lead to an overload or overheat. This my be your problem, otherwise; you may simply be a bit low on refrigerant.

 

[AZ Jeff]

The computer can sense the load on the engine via several of the sensors. It will cut off the AC temporarily if it thinks it will lead to an overload or overheat. This my be your problem, otherwise; you may simply be a bit low on refrigerant.

There is a difference between having the air stop coming out of the vents on the dash and the AC compressor stopping under heavy load.

If the various posters here are experiencing a loss of air discharge out of the AC vents in the dash when the engine is under heavy load, then the ONLY cause for that is loss of vacuum. A vacuum diagram, and a vacuum pump are the way to track this down.

There ARE some engine control systems that shut off the compressor when the engine is under heavy load or at WOT. That kind of action, however, will NOT cause the blower motor to stop pumping air out of the AC registers in the dash. The only effect you will notice is the air will become less cool while the compressor is temporarily shut off.

 

[corbinafly]

There is a difference between having the air stop coming out of the vents on the dash and the AC compressor stopping under heavy load.

If the various posters here are experiencing a loss of air discharge out of the AC vents in the dash when the engine is under heavy load, then the ONLY cause for that is loss of vacuum. A vacuum diagram, and a vacuum pump are the way to track this down.

There ARE some engine control systems that shut off the compressor when the engine is under heavy load or at WOT. That kind of action, however, will NOT cause the blower motor to stop pumping air out of the AC registers in the dash. The only effect you will notice is the air will become less cool while the compressor is temporarily shut off.

x2

 

[ErikL]

Just a thought.... but with the problem im having, could it be the speed of the outside air and the speed of the air coming to the AC blower are too similar...... kind of like driving 35mph with a 35 mph tailwind and sticking your hand out the window and not feeling the wind?

 

[Cliff]

AX Jeff you have hit the nail on the head that is exactly what my xj is doing loosing vacum. when i find some time im going to try and track down the leak. is there any negative effects my loosing vacume could cause with the more vitle systems brakes ect im not shure what all the xj uses the vacume system for.

thanks for any help you can give me im good with electric but fixing trucks is a new thing to me.

 

[Bradlybob]

I had a simular issue several years ago. Some battery acid had leaked out of a cheap battery and melted a vac line down in that area, as well as everything else it touched.

 

[seanman]

I had a simular issue several years ago. Some battery acid had leaked out of a cheap battery and melted a vac line down in that area, as well as everything else it touched.

Same thing battery acid ate through the vac line on my 99. I cut out the bad section of tubing and sleeeved it with soft vacuum hose. It didn't fix it. It still redirects the AC to the window defrost under load.