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no heat....

G

goin4wheelin

NAXJA Forum User
Location
TN
i change the heater valve but the problem is still there. it blow air, not hot air. what else could it be? thermostat? i check on the return line at the pressure bottle on the engine bay and all the line seem to be warm. could it be the heater coil?
and i did notice that the air compressor kick on and off when the heater's running.

the heater running fine last year but this year's just blowing cold, well, luke warm air instead of hot air.

it's my in-law jeep, 88, 4.0L w/ 240k miles stock
 
goin4wheelin said:
i change the heater valve but the problem is still there. it blow air, not hot air. what else could it be? thermostat? i check on the return line at the pressure bottle on the engine bay and all the line seem to be warm. could it be the heater coil?
and i did notice that the air compressor kick on and off when the heater's running.

the heater running fine last year but this year's just blowing cold, well, luke warm air instead of hot air.

it's my in-law jeep, 88, 4.0L w/ 240k miles stock
Click to expand...
Tried a backflush of the heater core?
 
Check the flapper valve under the dash on passenger side towards the center console...
On my '88 the cable that opens and closes it got disconnected.

I can't remember which position controls the heat, try it open and closed
 
pull the hoses off the core and flush it both ways,even after a machine flush my wifes 98 had no heat until I flushed the heater core.
Wayne
 
what he said also the ac comeing on and off is normal if you have your heat on defrost it is supposed to dry the air and defrost faster (i use my ac for oba and have had no probs with it not defrosting)
 
where's the heater core? is it in on the engine bay, under the glove compartment?

got pics of how it look like?
 
Just follow the 2 heater hoses to where they go into the firewall on the passenger side. Remove and plug them both, and run a garden hose through both sides of the heater core. It will flush plenty of rust and sediment out of the heater core. I had the same problem in my 88 with 240,000 miles. Works fine now that I flushed it.
 
Madmark said:
Just follow the 2 heater hoses to where they go into the firewall on the passenger side. Remove and plug them both, and run a garden hose through both sides of the heater core. It will flush plenty of rust and sediment out of the heater core. I had the same problem in my 88 with 240,000 miles. Works fine now that I flushed it.
Click to expand...


do you mean doing it on the engine bay? start fromt he heater valve hose and the return line from the firewall?
 
Madmark said:
Just follow the 2 heater hoses to where they go into the firewall on the passenger side. Remove and plug them both, and run a garden hose through both sides of the heater core. It will flush plenty of rust and sediment out of the heater core. I had the same problem in my 88 with 240,000 miles. Works fine now that I flushed it.
Click to expand...

Be careful of the pressure. I've heard that some towns' water pressure is several times the pressure some heater cores can stand. Maybe you should check this out before you start flushing w/a hose.
 
Churchlady said:
Be careful of the pressure. I've heard that some towns' water pressure is several times the pressure some heater cores can stand. Maybe you should check this out before you start flushing w/a hose.
Click to expand...

Postscript to that: town water pressure can be as much as 60-70 lbs. Some Chrysler heater cores (those in Dodges, at least) can stand only 15 lbs.
 
You are doing it all from under the hood. If you are careful unhooking and plugging the heater hoses, you will only loose the coolant that is in the heater core. The 88 closed cooling system is a pain to burp out all of the air from the system. I converted mine to a standard type radiator at the same time. Churchlady has a good point about water pressure. Start slowly since your heater core is already partially plugged, and use only enough pressure to flush all of the gunk out.
 
Dont forget to check to see if the engine is getting warm. (could be the thermostat) drive it around for a while and watch the temp guage. it should rise. if it doesnt look into the thermostate issue.
 
I had the same problem on my 89 found that the cable that hooked to air door under dash was not anchored allowing housing and cable to move when control moved was easy to fix with an zip tye.....works great now
 
goin4wheelin said:
i change the heater valve but the problem is still there. it blow air, not hot air. what else could it be? thermostat? i check on the return line at the pressure bottle on the engine bay and all the line seem to be warm. could it be the heater coil?
and i did notice that the air compressor kick on and off when the heater's running.

the heater running fine last year but this year's just blowing cold, well, luke warm air instead of hot air.

it's my in-law jeep, 88, 4.0L w/ 240k miles stock
Click to expand...

Check the engine temp! If you have a temp light then find a thermometer or something to check the water temp in the radiator. If you can't find that then feel the upper radiator hose when it with the motor warmed, it should be almost hot to touch. If it's not hot, then probably the t-stat is broke or stuck open. That's what happened in my 93, it broke into pieces. Cheap fix. You gotta have hot water to get heat:)

FUNKYTEE5
 
yeah, my 93, same thing, t-stat broke and stuck open, wouldent get hot enough to make the heater work. wouldent even get hot enough to move the gauge in the winter
 
same problem here, but i figured out that if you start your car and have the heater on low until it warms up,it works. Make sense? It is getting late, I can't type.
 
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