Check flushing the heater core threads. A lot of info here.

 

Even at 190 you should get hot air out. Check the blend door and flush the heater core. As for the difference in temp, I've had a number of thermos and none were really exact. Not something to worry about.

 

Thermostat could be stuck open. Thats why your not getting to temp, and no heat.

 

Agree on the thermostat. I would start there and then move on to the heater core if it keeps giving issues.

No at 190 it is plenty hot. I've run temporarily with no thermo and still had heat. It took longer to reach temp, not as hot 170 ish and threw a code but the heat was coming out.

 

Agree on the thermostat. I would start there and then move on to the heater core if it keeps giving issues.

 

Check the heat with the vehicle not running and see what you get. Not really sure of any other methods to suggest that aren’t previously posted.

 

Check the heat with the vehicle not running and see what you get. Not really sure of any other methods to suggest that aren't previously posted.

what?

The heat thats coming out of your vents is created by the engine. How are you suppose to get heat if it's cold and not running??

A thermostat is easy to replace, if it hasn't been done your not hurting anything by putting in a new one. Cheap too! Also freshen up the coolant, old coolant can loose it's ability to absorb heat.

 

Both heater hoses hot? Or is one cooler?

 

With it reaching 190* and it being a 1997 I'm sure the heater core is clogged, at least partially. Just remove both 3/4" hoses going to the firewall and force water through the connections. Both ways. You should see a bunch of crap flow out. I had to do this two falls in a row but its been fine since.

 

Just remove both 3/4" hoses going to the firewall

They're not both 3/4" hoses...

 

Ah ok, whatever the f they are.

 

11/16th's and 5/8th's

 

I had the same problem in my tj. I flushed the heater core, and it helped a little maybe, but not significant. Next I might try the thermostat. Me neighbor-mechanic recommended doing that. Has anybody had success?

 

If it was faulty than yes you would have success. Cheap, easy to do.

 

We got a flush kit to flush the heater core this weekend. I'm kind of leaning toward thinking it's a clogged core. If that doesn't do the trick, we'll go ahead and put a new thermostat in.

Chris - not sure about the hoses. Will give them a check tomorrow to see if both are hot.

Thanks for the replies, guys! Tomorrow morning is suppose to be 17 degrees. I might need to dress in 5 layers of clothes!!!

 

We got a flush kit to flush the heater core this weekend. I'm kind of leaning toward thinking it's a clogged core. If that doesn't do the trick, we'll go ahead and put a new thermostat in.

Chris - not sure about the hoses. Will give them a check tomorrow to see if both are hot.

Thanks for the replies, guys! Tomorrow morning is suppose to be 17 degrees. I might need to dress in 5 layers of clothes!!!

If both hoses to the heater hose are hot to the touch then you don't need a heater core flush.

 

Flush the heater core first. If you get lots of gunk. Flush the coolant system too.
$1 of pervention can = $100's in fixes.

 

did it work

you said you were going to flush the heater core but then you didnt update. I would like to know if you ended up changing the thermostat or if cleaning the core worked. Thanks.

 

TJ Heat Not Truly Hot???

Hi Guys, Just to say a good word, I know that this thread is a little old but I I myself was experiencing the same issue on my 97 Sahara. I began with isolating the heater core, buying a Prestone Flush Kit, using the garden hose. After flushing a few times and seeing some dirty mix, I decide to make a very diluted mix of warm water and CLR (I mean Weak), allowing the mix to set for about ten minutes I flushed the heater core through the hoses, both ways, through inlet and outlet, for about fifteen minutes to attempt to remove all the CLR. Okay, so after completing this I did have an improvement with the heat going from luke warm to warm. I wanted true heat, as my '93 YJ will toast you out, I knew the TJ wasn't completely working to its capabilities. Soo..I decided to flush the entire cooling system, since I had bought this TJ a few months ago, I had no clue on how often the system had been maintained. I went with Zerex (G-05) and Distilled Water. After draining and flushing about five times (1 hr), I did so trying to get all old coolant out, since it was Orange (Dexcool or forbid Original) I did not want to mix the two. Once the coolant ran clear the last two drains, I completely emptied one last time. Now since I had it all apart I decided to change the thermostat, since it was taking forever to warm up and compared to YJ, not where it should have been. So after changing thermostat, replacing with correct coolant, I went from warm heat to hot heat. Following day, after experiencing passenger floor water, I ended up pulling the blower motor out to seal up with RTV sealant, and this is the kicker. I simply could not believe the gunk built up against the heater core from assuming the cowl drain leaking after being clogged (cleaned out weeks prior). After cleaning out the gunk against the heater core, shop vac and fingers, I reassembled blower motor. With winter coming up, I am assured I have heat, believe me, little efforts (time and about $40 bucks) I have a new thermostat, fresh coolant, clean cowl drain, sealed blower motor and A/C drain, and most importantly, no water leaks and lava heat. Sorry for the length, just wanted to share all attempts and what showed best results, in the end all efforts minimal made great strides for what I was wanting and expecting.

 

Hi Guys, Just to say a good word, I know that this thread is a little old but I I myself was experiencing the same issue on my 97 Sahara. I began with isolating the heater core, buying a Prestone Flush Kit, using the garden hose. After flushing a few times and seeing some dirty mix, I decide to make a very diluted mix of warm water and CLR (I mean Weak), allowing the mix to set for about ten minutes I flushed the heater core through the hoses, both ways, through inlet and outlet, for about fifteen minutes to attempt to remove all the CLR. Okay, so after completing this I did have an improvement with the heat going from luke warm to warm. I wanted true heat, as my '93 YJ will toast you out, I knew the TJ wasn't completely working to its capabilities. Soo..I decided to flush the entire cooling system, since I had bought this TJ a few months ago, I had no clue on how often the system had been maintained. I went with Zerex (G-05) and Distilled Water. After draining and flushing about five times (1 hr), I did so trying to get all old coolant out, since it was Orange (Dexcool or forbid Original) I did not want to mix the two. Once the coolant ran clear the last two drains, I completely emptied one last time. Now since I had it all apart I decided to change the thermostat, since it was taking forever to warm up and compared to YJ, not where it should have been. So after changing thermostat, replacing with correct coolant, I went from warm heat to hot heat. Following day, after experiencing passenger floor water, I ended up pulling the blower motor out to seal up with RTV sealant, and this is the kicker. I simply could not believe the gunk built up against the heater core from assuming the cowl drain leaking after being clogged (cleaned out weeks prior). After cleaning out the gunk against the heater core, shop vac and fingers, I reassembled blower motor. With winter coming up, I am assured I have heat, believe me, little efforts (time and about $40 bucks) I have a new thermostat, fresh coolant, clean cowl drain, sealed blower motor and A/C drain, and most importantly, no water leaks and lava heat. Sorry for the length, just wanted to share all attempts and what showed best results, in the end all efforts minimal made great strides for what I was wanting and expecting.

I have seen that stuff destroy some cooling system parts before. I would never put it in my radiator, like it says on the bottle. :thumbdown:

 

I only put a weak mix of what I am assuming you’re referring to as the CLR, like barely any, into the heater core, and flushed it out for almost twenty minutes. Pretty sure it is fine, I only did so after reading probably two hundred comments on “it’s fine” and “it’ll eat away at all the core”, and basing it on the fact that guys did this 5 years ago and still no issues. Though I completely agree, never in the radiator. I know the heater core is essential a mini radiator, the water mix was hardly even tinted.

 

I only put a weak mix of what I am assuming you're referring to as the CLR, like barely any, into the heater core, and flushed it out for almost twenty minutes. Pretty sure it is fine, I only did so after reading probably two hundred comments on "it's fine" and "it'll eat away at all the core", and basing it on the fact that guys did this 5 years ago and still no issues. Though I completely agree, never in the radiator. I know the heater core is essential a mini radiator, the water mix was hardly even tinted.

For me when the people who make a product suggests not to use their product in radiators there must be a reason for that we may not know. I'm sure just using a little bit isn't okay either.

But hey, if you want to take that chance, it's all yours.

 

I've done both replace the thermostat and flush the heater core, still only luke warm air. the heat also only sometimes works. i think it might be the control panel or a blower motor resistor? i don't know

 

i have a 99 tj and the heat coming out is only luke warm. i replaced the thermostat, and that did nothing. i flushed out the heater core and that helped the heat feel a little bit hotter but not much. now the heat randomly cuts in and out if i play with the controls. I'm thinking its the control panel or maybe the blower motor resistor. any ideas or similar problems?