Dave88 Posted January 27, 2009 Share Posted January 27, 2009 Ok the heater Coil in my comanche is getting hot (it must be because the line going in and out are 140 deg.) I was thinking a door isnt opening or something. But i can hear a clicking or a slamming noise when i switch to heat my blower is fine.. this is getting on my nerves now. anyone have this problem and know how to fix it? Link to comment Share on other sites More sharing options...
mvusse Posted January 27, 2009 Share Posted January 27, 2009 There's a vacuum controlled valve on the hose to the heater core under the hood. If the vacuum line came off, the valve defaults to open. But even if coolant is circulating through the heater core, unless the heater control is set to warm/hot, the air should not travel through it to het warmed up. With the heater controls set to cold I have noticed no difference in cabin temperature between the valve being open (disconnected) and the valve being closed. Link to comment Share on other sites More sharing options...
aemsee Posted January 27, 2009 Share Posted January 27, 2009 Heater? It's 4 degrees here right now. You're in Florida, what do you need heat for! :fs1: . JK. So your fan works OK, You hear the blend door open all the way when you go to heat (that, by the way, is called the 'thud :D ' test. Technical term). How about air flow? When you move through Def, floor,blend,panel etc, does the air come out the proper vents? When you have it on 'heat', feel the air flow velocity coming out on the floor, and change btwn hot and cold. The amount of air should not change. If it is reduced when you put it on 'hot', you may have something blocking the heater core. I have seen the foam come off of the doors and get stuck on the heater core restricting flow and causing low heat, or it could be an armadillo is living inside there :yes: . I also think you should have more than 140 degrees at the core. With the truck fully warmed up, check the hoses. If they are at engine temp at the head and pump, and get colder as you go toward the firewall, you may have a plugged up core. Pull both hoses (afetr it cools of course :doh: ) and try to flush it out. Good luck and enjoy those chilly 60's and 70's down there :cheers: Link to comment Share on other sites More sharing options...
Randy in Maine Posted January 27, 2009 Share Posted January 27, 2009 My heater has recently gone "lame" and only blows lukewarm air. It is close to 0º this morning and the temp gauge moves to about 200º after about 1.5 miles and then drops a little when the thermostat opens and then comes back up and stays at about 200º. The level of coolant in the plastic bottle is correct. Cap seals well. It has the AC if that matters. The fan only works on high anymore. I have not tested the temperature of the coolant with a different thermometer yet. The location of the blow changes as I change the lever from defrost, heat, vent, etc. so I think that portion is working OK. There is no change in the volume of air when I move the temperature lever from cold to hot and back. Just where would the vacuum line be located that may be my problem? Thanks in advance! Link to comment Share on other sites More sharing options...
Pete M Posted January 27, 2009 Share Posted January 27, 2009 The fan only works on high anymore. That is usually an indication of a blown resistor pack. (when the resistors are blown, it generally leave HIGH as the only choice) It is located next to the passengers feet and looks like a little cover held to the air duct by a little screw or 2. Be careful though, as a dying blower motor has been known to pull too many amps and slowly kill the resistor pack, and if that's the case it'll eventually take out the new one too. I recommend getting a functioning resistor pack from the nearest pull a part junkyard for cheap and trying that. I do believe they are available at the dealerships still. :thumbsup: Link to comment Share on other sites More sharing options...
aemsee Posted January 27, 2009 Share Posted January 27, 2009 My heater has recently gone "lame" and only blows lukewarm air. It is close to 0º this morning and the temp gauge moves to about 200º after about 1.5 miles and then drops a little when the thermostat opens and then comes back up and stays at about 200º. The level of coolant in the plastic bottle is correct. Cap seals well. It has the AC if that matters. The fan only works on high anymore. I have not tested the temperature of the coolant with a different thermometer yet. The location of the blow changes as I change the lever from defrost, heat, vent, etc. so I think that portion is working OK. There is no change in the volume of air when I move the temperature lever from cold to hot and back. Just where would the vacuum line be located that may be my problem? Thanks in advance! HOLY :hijack: BATMAN Link to comment Share on other sites More sharing options...
oldrusty Posted January 27, 2009 Share Posted January 27, 2009 My heater has recently gone "lame" and only blows lukewarm air. It is close to 0º this morning and the temp gauge moves to about 200º after about 1.5 miles and then drops a little when the thermostat opens and then comes back up and stays at about 200º. The level of coolant in the plastic bottle is correct. Cap seals well. It has the AC if that matters. The fan only works on high anymore. I have not tested the temperature of the coolant with a different thermometer yet. The location of the blow changes as I change the lever from defrost, heat, vent, etc. so I think that portion is working OK. There is no change in the volume of air when I move the temperature lever from cold to hot and back. Just where would the vacuum line be located that may be my problem? Thanks in advance! Check the plastic tube that runs across the passenger inner fender behind the battery. If you've had the battery out for any reason and werent careful that line is easily cracked or broken. don't ask me how I know. :doh: Link to comment Share on other sites More sharing options...
Dave88 Posted January 27, 2009 Author Share Posted January 27, 2009 I saw that vaccum line. It opens and closes a door. Only opens when i turn the A/c on. Ventalation is fine, i blows out the same amount of air through all the vents. only thing i don't get is that The IN and OUT lines are boath around 140-180 degrees. I don't see any coolant in my cab or anything leaking anywhere. OhH and, Theres a small brittle I'm guessing vaccum line coming out of my A/C txv and my heater txv. and their both not connected to anything. so i think its meant to be connected. there both the same color etc.. Can someone look at their jeep and tell me. :hmm: Link to comment Share on other sites More sharing options...
mjeff87 Posted January 28, 2009 Share Posted January 28, 2009 txv....now there's a term not often uttered. You do refrigeration for a living ;) ? Yes, those lines need to be connected (one should be pink and one black, but that's beside the point). There's a vaccuum operated valve that opens/closes the coolant supply to the heater core, and those lines control it. When you move the HVAC lever in the cab, not only does it send a vac signal to the plenum to direct air movement, it also sends a vac signal to that valve to open and circulate coolant thru the heater core (XJ/MJ only, YJ/TJ's don't have that and have constant flow thru the core). Connect one of your lines to the vac line that comes from under the battery tray (mentioned earlier) to provide the vac signal, and the other line to the diapraghm on the heater control valve. Then you'll have circulation thru the heater core, and warmth ;) Jeff Link to comment Share on other sites More sharing options...
Dave88 Posted January 28, 2009 Author Share Posted January 28, 2009 I could kiss you jeff. And yeah i do refrigeration :D But mine are both white.. ill connnect them and prey for the best Link to comment Share on other sites More sharing options...
Dave88 Posted January 28, 2009 Author Share Posted January 28, 2009 Damn, got my hopes up.. I'm talking about a hose under the hood.. Link to comment Share on other sites More sharing options...
mjeff87 Posted January 28, 2009 Share Posted January 28, 2009 yeah, I'm talking about under the hood too......right beside where the HVAC fan motor is, up on the firewall. There should be two hard plastic vac lines coming out of a foam-type recatangular block....they are the lines I'm refering to. They control the valve that lets coolant pass thru the heater core: Image Not Found Link to comment Share on other sites More sharing options...
mvusse Posted January 28, 2009 Share Posted January 28, 2009 One of those is the vacuum supply line that provides the vacuum source to the heater controls. It hooks up to the main vacuum line coming from the reservoir in the bumper. The other one goes to the valve that controls the coolant flow. Link to comment Share on other sites More sharing options...
aemsee Posted January 28, 2009 Share Posted January 28, 2009 he said all his modes work fine. If neither of the lines are hooked up, no vacuum to the control head, no way modes can change, it would default to defrost. He must be talking about something else? Link to comment Share on other sites More sharing options...
jtdesigns Posted January 28, 2009 Share Posted January 28, 2009 Ok the heater Coil in my comanche is getting hot (it must be because the line going in and out are 140 deg.) I would still flush out the heater core. I bet some trash has stopped up a few of the rails and still let enough fluid to get by and heat the lines.. I was having the same problem, then one day, I just though I'd give it a try. Its to easy to remove the heater lines and run some water though it. Worked for me, but I didnt get a temp on the lines they both just felt warm to the touch. Maybe if there was a way to actully put your hand up on the heater core to see if its warm, or shoot it with a laser to get a temp.. Is there a way to actully check the temp of the heater core inside the box????? I don't know, but would be a good way to troubleshoot it. Link to comment Share on other sites More sharing options...
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