stevekop Posted March 15, 2017 Share Posted March 15, 2017 Cold here in the northeast. Comanche not putting out enough heat, air warm at most. Maybe thermostat? Any Ideas Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 15, 2017 Share Posted March 15, 2017 Do you have a temp gauge or idiot light on the dash? I'm assuming a light since you're asking about engine temp. Your truck should have a 195* thermostat, and OEM Mopar (p/n 83501426) is the best one to keep your engine running at optimum temperature year round. Another cause of insufficient heat is a clogged heater core. Disconnect the heater hoses from it and backflush it out thoroughly with a water hose and see if that helps. Link to comment Share on other sites More sharing options...
Dzimm Posted March 15, 2017 Share Posted March 15, 2017 Do you have a temp gauge or idiot light on the dash? I'm assuming a light since you're asking about engine temp. Your truck should have a 195* thermostat, and OEM Mopar (p/n 83501426) is the best one to keep your engine running at optimum temperature year round. Another cause of insufficient heat is a clogged heater core. Disconnect the heater hoses from it and backflush it out thoroughly with a water hose and see if that helps. X2 on the heater core. You can replace thermostats all day long but if the heater core is clogged you won't get any heat. When back flushing mine I had to duct tape the garden hose to the heater hose so it would have enough pressure to blow the clog out. Keep in mind that when you put too much pressure through it you run the risk of it blowing a hole and soaking your floorboard. Link to comment Share on other sites More sharing options...
Gene Posted March 15, 2017 Share Posted March 15, 2017 All of the above is right on the nose. But here's another way that might be helpful to look at it… There would be three main causes for lack of heat. One would be the engine is not getting hot enough, the second would be that the heater core is blocked or not receiving the hot coolant, the third would involve the position of the airflow door under the dash. If you run the vehicle for a while, and carefully touch the large hose coming over to the radiator, this should be hot. Too hot to hold, hot enough that you'll only touch it for a second. If the hose is not this hot, then thermostat would be a suspect. If the radiator hose is getting hot, then feel the heater hoses, and see if they feel as hot. Hot radiator hose, but cool heater hoses, would go along with clogged heater core. There's also a vacuum valve on the heater lines, this could have failed shut. Finally, underneath the dash, there is ducting, and and air door to determine how much of the inside air goes through the heater core. The door may have failed. It's operated by a vacuum switch, that could be having a problem too. Hope this helps! Gene Link to comment Share on other sites More sharing options...
Eagle Posted March 15, 2017 Share Posted March 15, 2017 Cold here in the northeast. Comanche not putting out enough heat, air warm at most. Maybe thermostat? Any Ideas Clogged heater core. Link to comment Share on other sites More sharing options...
Ωhm Posted March 15, 2017 Share Posted March 15, 2017 Did you ever have hot air during the winter months or did this just start today? Link to comment Share on other sites More sharing options...
cruiser54 Posted March 16, 2017 Share Posted March 16, 2017 Heater control valve not opening? Link to comment Share on other sites More sharing options...
64 Cheyenne Posted March 16, 2017 Share Posted March 16, 2017 Heater control valve not opening? If you still have this ^^^ I recommend you delete it. Eliminate a possible problem area, which the factory did anyway with the in later XJ years Link to comment Share on other sites More sharing options...
87Warrior Posted March 17, 2017 Share Posted March 17, 2017 Heater control valve not opening?That POS failed in bypass mode on me one cold day a hundred miles from home. It went into the trash the next day. Link to comment Share on other sites More sharing options...
Marine1Texas Posted March 17, 2017 Share Posted March 17, 2017 I turned the valve in to a manual valve, winter time I turn heater on all the time, summer time no fluid circulates in to the heater core at all. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 17, 2017 Share Posted March 17, 2017 I turned the valve in to a manual valve, winter time I turn heater on all the time, summer time no fluid circulates in to the heater core at all. Okay to do, but not necessary. Link to comment Share on other sites More sharing options...
Marine1Texas Posted March 17, 2017 Share Posted March 17, 2017 true that! however in middle of summer down here in Texas when it is hot and humid I my self don't want any heat at all in the cab! :) Link to comment Share on other sites More sharing options...
cruiser54 Posted March 17, 2017 Share Posted March 17, 2017 true that! however in middle of summer down here in Texas when it is hot and humid I my self don't want any heat at all in the cab! :) Well, I'm in Arizona!!! LOL. I have found that if the blend door is properly adjusted, there is no heat in the cab. I also like the fact that stuff is moving and not stagnating in the heater core for a lot of the year. Link to comment Share on other sites More sharing options...
Eagle Posted March 17, 2017 Share Posted March 17, 2017 I also like the fact that stuff is moving and not stagnating in the heater core for a lot of the year. ^^^ This. Letting the coolant sit idle in the heater core all summer is what promotes clogging. There's a reason why Jeep eliminated that valve in the newer XJs. Link to comment Share on other sites More sharing options...
SBpunk Posted March 17, 2017 Share Posted March 17, 2017 Small cab with a blower/heater built for an XJ = massive heat when its working properly. Like everyone said flush the heater core, put in new coolant and make sure its not leaking at the little plastic piece before it goes into the firewall. I ended up bypassing it and my heat gets insanely hot even during the winter. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 17, 2017 Share Posted March 17, 2017 Small cab with a blower/heater built for an XJ = massive heat when its working properly. Like everyone said flush the heater core, put in new coolant and make sure its not leaking at the little plastic piece before it goes into the firewall. I ended up bypassing it and my heat gets insanely hot even during the winter. That little plastic thing is a disaster waiting to happen. HCV Removal The heat is controlled by the blend air door. I've eliminated at least 10 of them here in Arizona and my AC always works perfectly. Actual field experience has proven time and time again, by numerous different people, that there is NO downside to eliminating the HCV.. It flat works. Period. The other benefits are keeping coolant flowing versus being stagnant in the heater core and the dangers/disastrous results of having a valve fail unexpectedly whether you're poking around the engine bay or driving down the highway or trail. Link to comment Share on other sites More sharing options...
SBpunk Posted March 17, 2017 Share Posted March 17, 2017 Small cab with a blower/heater built for an XJ = massive heat when its working properly. Like everyone said flush the heater core, put in new coolant and make sure its not leaking at the little plastic piece before it goes into the firewall. I ended up bypassing it and my heat gets insanely hot even during the winter. That little plastic thing is a disaster waiting to happen. HCV Removal The heat is controlled by the blend air door. I've eliminated at least 10 of them here in Arizona and my AC always works perfectly. Actual field experience has proven time and time again, by numerous different people, that there is NO downside to eliminating the HCV.. It flat works. Period. The other benefits are keeping coolant flowing versus being stagnant in the heater core and the dangers/disastrous results of having a valve fail unexpectedly whether you're poking around the engine bay or driving down the highway or trail. Concur. I had no issues with my AC or heat when I deleted it and ran straight lines. Constant smell of coolant went away and everything works great. It only cost about 15 bucks tops and that was with enough to have extra line just incase down the road. Link to comment Share on other sites More sharing options...
Marine1Texas Posted March 17, 2017 Share Posted March 17, 2017 yes no flowing coolant can cause clog, I drain what is left after I divert the coolant. My blend door works but there is a crack in the door, and I won't be fix till I need to pull the hvac out box back out, on heater core replace or something of that nature. I am down to one MJ the 87 now anyway. the 88 got totaled with the new 4.6 in it. semi truck ran it completely over in the parking lot at mccoys! he lost his breaks and says he did not see it, big bummer for that little work truck! Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 17, 2017 Share Posted March 17, 2017 Damn, sorry to hear about your 88 w. the 4.6 Clifford engine Nori. Did you salvage the engine? Link to comment Share on other sites More sharing options...
Marine1Texas Posted March 18, 2017 Share Posted March 18, 2017 nothing at all was remotely salvageable. Looked as if the front of the ax15 just broke off in the bellhousing. I am pretty sure the bottom of the block got cracked. The engine was pointing at around 45 degrees and the trans was smooshed on the pavement between the body and the cement. the rear of the truck looked better then the front. It was a loaded flat bed that some how just rolled over the passenger door. I never seen a front drive axle broke like that before. The insurance paid enough to get a 2012 f250 super duty with 80k on it. One of my ranch hands was in mccoys when they herd the crash. I came down to see what happen and I was floored to see that little blue truck like a pancake in the front. Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 18, 2017 Share Posted March 18, 2017 Just sitting there minding her own business and gets pancaked. May she RIP. :( It good you got a decent settlement...... Link to comment Share on other sites More sharing options...
Marine1Texas Posted March 18, 2017 Share Posted March 18, 2017 Yea the company that hit the truck was very quick to get me what it was insured for. Since it is a farm truck and I have employees drive it full coverage with extra, insured the price of the rebuild. So I came out about 2000 ahead of what I had it insured for. Sad to see all my work I put in to the truck go down the hill. I am just glad none of my ranch hands were in the truck when it happened. Link to comment Share on other sites More sharing options...
1989 comanche mj Posted March 18, 2017 Share Posted March 18, 2017 If the heater core is clogged externally like with leaves twigs and debris that will lower heat flow also. And if your blower motor isn't getting full voltage or the motor is tired. Link to comment Share on other sites More sharing options...
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