Heater blows luke warm not hot??

[hoodwink]

newbie here.. tried the search, but nothing.. so my question is, is this a common issue w/xj's? just picked up a 99xj 4.0 last week and turned on the heat the other day and it doesnt get hot at all?? now, both heater core lines are hot so im assuming the thermostat is ok right? ive been reading that maybe a reverse flush of the heater core might help??

and my last question is, is my jeep supposed to have a "Heater Control Valve"?? looking at teamcherokee's site they have a some for 99-01's.. well, i dont... just 2 lines from the wp/thermostat housing to the firewall... any help would be appreciated thx -Jason

[Begster]

Yes, your heater core is most likely clogged. My '99 and my dad's '01 blow amazingly hot air. Another '99 I got rid of last year didn't blow hot air, and when I parted it out, I found the heater core was completely clogged with junk.

No, you're not supposed to have a heater control valve like the older Cherokees.

[RadioShackSpecial]

Sounds like someone already tried to flush the core. Probably broke the HCV when taking the hoses off. Its okay to bypass it, just means hot coolant will be running through the heater core all the time (guess not in your case). The blend door separates the hot and cold side so it should not make a difference in the summer.

You could try flushing it but it may need to be replaced. Is Florida not warm? I know here the heater is the first thing I check before buying any vehicle.

[Tim_MN]

Newer Cherokees do not have a heater control valve. Low heat can be caused by a lazy thermostat, a clogged heater core, a failing air blend door, or a water pump with a poor flow rate.

Start with a basic cooling system service.

-Use a flushing/cleaning solution and then drain and fill the radiator with a fresh 50/50 coolant and water mix.
-Back flush the heater core with a low or medium water flow from the garden hose. High pressure water or compressed air will ruin your heater core.
-Inspect the radiator for mud/bugs/grass clogging the outside and mineral deposits clogging the inside.
-Replace the thermostat with a STANT or Robertshaw 195* thermostat. Cheap thermostats are cheap for a reason.
-Replace the radiator cap if your Jeep has one. An old worn out cap will allow boil overs and/or allow the coolant flash over into to steam. You will see the coolant temps suddenly jump from 210* to the Red Zone and back to 210* if your radiator cap is weak.
-Replace the water pump. The pumping fins can deteriorate over time and the pump will not flow enough coolant to keep the temps under control.
-Inspect/replace the radiator hoses. Make sure the coiled wire is installed in the lower hose.

[hoodwink]

half way through the flush.. went and bought a 195 thermostat and took off the housing and to my surprise, NO THERMOSTAT??? so how would not having one affect the system? was it the cause of no "hot" air? also, flush/reverse flushed the heater core.. looked like chocolate milk... gonna go seal it up, fill, empty, then fill w 50/50.. any steps im missing?

[Begster]

Originally Posted by hoodwink

half way through the flush.. went and bought a 195 thermostat and took off the housing and to my surprise, NO THERMOSTAT??? so how would not having one affect the system? was it the cause of no "hot" air? also, flush/reverse flushed the heater core.. looked like chocolate milk... gonna go seal it up, fill, empty, then fill w 50/50.. any steps im missing?

Chocolate milk is not good, how does your oil look? Has the Jeep ever been overheated? How does it run? I would think about having the engine compression tested and the cooling system pressure tested.

Chocolate milky liquid is usually a mix of oil and coolant, caused by a head gasket or cracked head.

[hoodwink]

i shouldve said rusty tea lol.. it was mostly reddish rust color.. oil looks clean, runs perfect, and as far as i can tell never been overheated? so i put it back together and works great.. heat is HOT now

[joe_peters]

Now that things are warming up, time for a cold beverage of your choice!

Glad you got it done.

[yardape]

I will NEVER buy a car from a hobbyist or shade tree mechanic again. Been there done that with my Grand Cherokee. Its unbelievable how stupid people will be and then leave all their time bombs for the next owner. Congratulations. Glad your mystery was solved.

Not to cast dispersions and I hope its not the case, but be aware that the thermostat may have been removed for a stupid reason,... like the wrong fix for an overheating issue. You'll find out in the summer. Or maybe your jeep just needed a good flush which had been neglected and you took care of.