I have a 93 cherokee 2.5L.Most of the time the heater is not putting out any heat, occasionally it works fine, like abot once every 2 weeks. Any ideas what is wrong? All fuses chec out ok. Thanks for any info that any one has.

Is the engine reaching operating temperature?

The fan blows but just cold air is that correct?

Andy

When it is blowing, its is pretty warm, although not as warm as it used to be.For the last 2 days it has been working, then it might go for a week without blowing anything. thanks for any ideas.

When it quits does it quit on all speeds.  Try High and see if it still works.

If so there is a resistor block that reduces the voltage for the lower speeds that could be burned out.

The intermittent deal sounds like a partially melted connector.  The main feed to the switch in the dash is the most likely place for that.

Andy

Check your control cables...that is THE most common problem (of which I have with my 95 YJ)...the ends break off, and even if your heater is working correctly, the air handler is set to vent, not heat.   Jon

I am also having heater troubles. My jeep sat for about 4 years before I got it running again. I tried the heater the other day and nothing happened. The blower motor didn't work and no heat came from the vents. Do you think that it might be the control cables? Brenda

It might be worth pulling out your heater controls to look, but first run through these first...   1. When your engine gets warm feel the heater hoses up by the firewall and see both are hot to the touch.  This will tell you if the heater core is getting hot fluid.   2.  If the fan is never coming on, check the blower fuse first.   3.  The blower fan only works when the top slide selector is set in the Defrost or Heat mode.  There is a cut out switch the disables it when you have the slider in Off or Vent.  This switch is located on the controls if you pull them out and might of got disconnected.   4.  The Air flow control is a vacuum activated device besides the cables the open and close flaps.  These control cable have hoops on the ends the snap on to the plastic pegs on those Slide Levers you see in the front.  These are VERY Fragile as they get old and break quite often.  It is a real problem with the YJs.  That Vacuum switch may also came loose or is unplugged.  The Tubes on mine were broke when I got my YJ and I had to get another heat control unit off Ebay.  So far thing are working great now.   5. The control cable need a drop of machine oil to keep them work smoothly.  3 in 1 machine oil or 20ASE will work just fine.  That is one thing that can cause these to break from to much resistance to move the cable inside the sleeve and then it snaps off one of those tabs I told you about earlier.   Let us know what you find, just start to eliminate one thing at a time and you will find it quickly, these systems are really simple.  Good Luck.   Brian R.  

From what you've told me I think I know what it probably will be-the vacuum actuated air flow control. The reason my jeep hadn't been running is the engine compartment caught fire 4 years ago destroying the left side of the compartment (hoses, sensors, wiring harness, etc.) and I have been fixing it up when money allowed for the last 4 years with the help of my dad. So with my luck it's probably going to be reason #4. Brenda

Cool I hope that helps you out.....  Nice to know another lady that's not a afraid of using a wrench.   Brian R.  

Thanks. This is all great information. Looks like a have a project for the weekend. Jason

I have an 87yj and my blower motor quit working a while back and i was frustrated when i could nto figure out why. finally after looking for the longest time i found the connector on the fire wall under the battery had come off. What a stupid place for a connector. Once i plugged it in Ops Check good!! Chuck

Well I finally got around to checking the heater out. The fan switch isn't getting any juice going to it. The A/C works so it's not the fan itself it's got to be the connection. Now I might have unhooked something when I replaced the wiring harness in my engine compartment while I was fixing it back up-but what could I have unhooked? The wires going to the heat controls seems to be hooked up. I checked the wiring diagram in my Chilton's manual but it shows the a/c connections and not the heater connections. Anyone got a pic or a diagram they can send me of the heater schematics? Brenda -- In

Brenda, Long time no chat. How is the Jeep otherwise? You had the engine compartment fire and replaced the harness with your dad, correct? Did you ever get the 4WD vacuum hoses straight? Check the fuses. You may not be getting power out of the fuse. You may have power going in to the fuse and not coming out of it. Your fuse pannel may be worn out. I had to put a bypass and a new in line fuse holder into mine. I would turn on the fan and it wouldn't come on. I had the engine on and the fan on then I slammed the door and it came on. Ended up the fuse holder was worn. I could test the fuse and I had power at the fuse, but the wire coming out had no power. I would start there. I think I got my service manual from Rosser Jeep. They sell the factory manual. I have no way of sending it to you. The power goes directly from the fuse to the switch. Start at the beginning and not the middle when you are working on an electrical circuit. Find out what you have from the start and where you lose it. That will be the least frustrating way to do it. John 87 YJ LIFE IS SHORT, EAT, SLEEP, JEEP

Thanks for the info John. I got it fixed already and it turned out to be something really simple which is amazing because nothing on my jeep has been easy or simple. It was just a wire that had come unplugged under the battery tray. I always want to make it harder than it really is. Otherwise the jeep is great. It's running smooth and purring like a kitten. I even have A/C!! I didn't know it worked but it does. I never figured out the vacuum hoses for the 4WD I bought a 4x4 posi lok for it instead off of Ebay. I'm going to install that this week sometime. I painted the hood and right front fender due to the paint peeling off. Having some trouble with it though. I used spray paint to do it and when I put a clear coat of Krylon crystal clear on it it looks like crap. I'm not sure if I got too close to the hood or what but you can tell where I painted with the crystal clear. So if anyone has any ideas on that I would appreciate hearing from you. I'm going to take some pics of the finished jeep but need to get the paint situation figured out. Then I will post the pics here on the website. Thanks for everyone's help. You guys are awesome!!!! Brenda

Brenda, get some 800 grit wet dry sandpaper and wet sand the area that is more dull. It should bring up some shine to match. If that doesn't work, just paint flames. It went through flames once, you can't do any more damage. I saw a Jeep with the same color that was in an accident. He painted a yellow graphic to cover the different color paint areas. I would probably go with a midnight blue graphic. Have fun. I am looking forward to the pics. John LIFE IS SHORT, EAT, SLEEP, JEEP

Brenda I had the same problem one day last winter my blower quit working. I had about enough and was ready to get rid of the jeep. I wasready to pull the blower out and bench check it when I figured out there was a plug under the battery tray and amazingly enough I plugged it in and wal la!!! Heat!!!!! Needless to say I still have the jeep. I just had the clutch, exhaust, and rear main seal replaced less than a month ago. Then I get brake fluid running down my floor board so then i replace teh clutch master cylinder. After that I'm still loosing clutch fluid, come to find out The slave cylinder that was just replaced is bad. Thank God it's covered under warranty. Sorry for rambling This honestly just started out to be about the plug under the battery. Take care Chuck

Replace the Clutch master cylinder. Some warranties won't cover it if the master isn't replaced. What happens is the master cylinder starts to deteriorate and sends metal filings into the slave cylinder. John LIFE IS SHORT, EAT, SLEEP, JEEP

Check your control cables...that is THE most common problem (of which I have with my 95 YJ)...the ends break off, and even if your heater is working correctly, the air handler is set to vent, not heat.   Jon

I am also having heater troubles. My jeep sat for about 4 years before I got it running again. I tried the heater the other day and nothing happened. The blower motor didn't work and no heat came from the vents. Do you think that it might be the control cables? Brenda

It might be worth pulling out your heater controls to look, but first run through these first...   1. When your engine gets warm feel the heater hoses up by the firewall and see both are hot to the touch.  This will tell you if the heater core is getting hot fluid.   2.  If the fan is never coming on, check the blower fuse first.   3.  The blower fan only works when the top slide selector is set in the Defrost or Heat mode.  There is a cut out switch the disables it when you have the slider in Off or Vent.  This switch is located on the controls if you pull them out and might of got disconnected.   4.  The Air flow control is a vacuum activated device besides the cables the open and close flaps.  These control cable have hoops on the ends the snap on to the plastic pegs on those Slide Levers you see in the front.  These are VERY Fragile as they get old and break quite often.  It is a real problem with the YJs.  That Vacuum switch may also came loose or is unplugged.  The Tubes on mine were broke when I got my YJ and I had to get another heat control unit off Ebay.  So far thing are working great now.   5. The control cable need a drop of machine oil to keep them work smoothly.  3 in 1 machine oil or 20ASE will work just fine.  That is one thing that can cause these to break from to much resistance to move the cable inside the sleeve and then it snaps off one of those tabs I told you about earlier.   Let us know what you find, just start to eliminate one thing at a time and you will find it quickly, these systems are really simple.  Good Luck.   Brian R.