# What can cause car to overheat with heater still blowing hot **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [July 22, 2019, 8:51pm UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020 "2019-07-22T20:51:15Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Cameron\_Gunn](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cameron_gunn/32/16826_2.png) [@Cameron\_Gunn](https://community.cartalk.com/u/Cameron_Gunn)\ **Post date:** [July 22, 2019, 8:51pm UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/1 "2019-07-22T20:51:15Z")
My 2005 Jeep Grand Cherokee 3.7 V6 is overheating but the heater is working. What could be the problem? ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [July 22, 2019, 9:05pm UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/2 "2019-07-22T21:05:45Z")
It could be a partial blockage in the coolant system, like the radiator, or a faulty thermostat. When was the last time you changed the coolant? ---
**Author:** ![Beancounter](https://avatars.discourse-cdn.com/v4/letter/b/59ef9b/32.png) [@Beancounter](https://community.cartalk.com/u/Beancounter)\ **Post date:** [July 22, 2019, 9:11pm UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/3 "2019-07-22T21:11:34Z")
When you park your car, look for any obvious coolant leaks (hoses, radiator, expansion tank, puddles, etc.) After it **completely** cools off, check your coolant level. If your coolant is normal and you don’t see any leaks, it may be as simple as a $10 thermostat replacement.but if the coolant is low and you don’t see any leaks, time to take it to a mechanic. ---
**Author:** ![It\_s-Me](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/it_s-me/32/12660_2.png) [@It\_s-Me](https://community.cartalk.com/u/It_s-Me)\ **Post date:** [July 22, 2019, 9:39pm UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/4 "2019-07-22T21:39:31Z")
From your other thread, You have a bunch of codes P0300 random misfires P1637 a problem with the alternator P0138 Faulty o2 sensor or short in the wiring to it P0522 Faulty oil pressure sensor or wiring, or low oil pressure P0420 Bad cat, or faulty wiring Plus it’s overheating You either have a major problem with the wiring, or your computer is shot. Would be best to get this car to a shop and spend the $200 to let them diagnose it, other wise you’ll just be throwing money at it and hoping you fix it. With it being a Jeep, my money is on the computer. ---
**Author:** ![Cameron\_Gunn](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cameron_gunn/32/16826_2.png) [@Cameron\_Gunn](https://community.cartalk.com/u/Cameron_Gunn)\ **Post date:** [July 22, 2019, 11:34pm UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/5 "2019-07-22T23:34:08Z")
Ok so I had a blown head gasket. My cousin put some Bars headgasket sealant and now I’m car is running perfect. The only issue is that it is still running hot but not completely on H. Do you still think it’s the Computer or is it still a pocket in the coolant system and I never actually bled it correctly like I thought I did. ---
**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\ **Post date:** [July 22, 2019, 11:43pm UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/6 "2019-07-22T23:43:17Z")
Maybe not quite perfect @Cameron_Gunn. Maybe just significantly better… for now. ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [July 23, 2019, 12:11am UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/7 "2019-07-23T00:11:19Z")
Is the radiator fan operating? ---
**Author:** ![Cameron\_Gunn](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cameron_gunn/32/16826_2.png) [@Cameron\_Gunn](https://community.cartalk.com/u/Cameron_Gunn)\ **Post date:** [July 23, 2019, 2:40am UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/8 "2019-07-23T02:40:02Z")
Yes the fan is operating. It turns on about 5 minutes into idling. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [July 23, 2019, 2:56am UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/9 "2019-07-23T02:56:58Z")
At this point I’d guess faulty thermostat, air pocket in the cooling system, cooling system isn’t holding pressure, the bars leak has improved the head-gasket situation but not totally fixed it, or faulty radiator cap. If I had that problem I’d replace the thermostat and the radiator cap, not b/c I know that’s what the problem is, but both are relatively inexpensive and you may get lucky. If that doesn’t work, at least you’ve eliminated the radiator cap and the thermostat. My hunch though is there’s still a head gasket problem. ---
**Author:** ![Cameron\_Gunn](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cameron_gunn/32/16826_2.png) [@Cameron\_Gunn](https://community.cartalk.com/u/Cameron_Gunn)\ **Post date:** [July 23, 2019, 7:08am UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/10 "2019-07-23T07:08:17Z")
The heater had stopped blowing hot and I had to bleed it again. After bleeding it the last time the heater started blowing heat again and the gauge has stayed in the middle. For now everything is doing ok. It’s been about 5 hrs. Tomorrow morning at crank up will be the real test ---
**Author:** ![Cameron\_Gunn](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cameron_gunn/32/16826_2.png) [@Cameron\_Gunn](https://community.cartalk.com/u/Cameron_Gunn)\ **Post date:** [July 23, 2019, 7:09am UTC](https://community.cartalk.com/t/what-can-cause-car-to-overheat-with-heater-still-blowing-hot/145020/11 "2019-07-23T07:09:25Z")
As long at it last until September then I’m good!