My heater works fine fan works thermostat seems to be good but all I get is cold air no heat
Flush the heater core, both directions.
The
orvis grand cherokee.97
the heater doet not work fine, its dead, only cold air
http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service
do you have the advance climate controls option.
that is key to all tests.
The AZC or climate controls must detect a need for heat.
automatic zone controls, or the like.. (not manual controls option)
the controller is called ATC.
page 24-12 starts heater testing in the FSM.
look there, now.?
if outside is 70F then dash heat will be 147F min. <<< spec,
page 12 tells you the hose tests. clear as day.
same page states, the manual system uses vacuum dampers.
is it?
if not its auto option.
if it is auto there is an LCD display above, temp control
and will show ER if there are errors
page 14 shows how to do the tests.
page 15 shows how to run the HVAC diagnostic, with no special tools.
(press 2 buttons at once , magic)
its all there to read .....
but many here hate books, so,,,, be that as it may be....
happy guessing....
You can remove the glovebox, push the passenger seat back and with a flashlight look at the end of the shaft of the blend door motor as you adjust it from cold to hot. If the shaft doesn't have 90 degrees or so of movement then: 1) the blend door itself could be blocked by an obstruction, 2) if it doesn't turn at all then the circuitry has detected that the shaft has broken and it won't engage the motor or 3) it's unlikely but the motor could be burned out. The usual case is that the shaft has broken on the flimsy blend door, the circuitry has detected the failure and that it simply refuses to rotate anymore = stuck with cold air.
Google: Jeep repair heater blend doors youtube
now lets do physics.
heat exchangers 101
hot water must flow fully thru the core.
and actually be hot water not 150F. 180F+ is correct.(tools called pyro guns work best)
the blower air must flow thru the core.
if the damper blocks this path, there will be no heat.
that is all you need, to know besides how to do simple tests. (ask how)
we cant touch the core but we can touch the core hoses. the fsm correctly states.
if both hose are hot , good.
if one is tad less, that is ok.
if one is super cold , that is core block.
case in point
180F on input hose.
here are 2 pyro gun readings on 70F day.
Heater hose top 156 (input)
Heater hose bottom, 147 (output 10f drop because fan is on and heat on... "exchanging heat it is......:")
the read top is 180f.
the lower 156 is the hose temp only, the pyro gun can only read rubber. temp
when you see 156f, it will be much hotter inside.
the themostat housing will read 180F if the stat is 180F . if housing is metal.
the metal will reach full 180F.
there you go , real numbers.
no bs.
fsm words (mine are 10degree less)
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SOURCE: Heater blows cold air
If the "Heater In Hose" gets hot, and the "Heater Out Hose" does not get hot, than either the Control Valve is sticking closed, or your heater core is plugged up with ****!
Have you used "Barrs Leak" or a simular product for a radiator leak? That will sometimes clog the heater core.
I have a 1993 Grand Cherokee, which "Normally" throws very hot air out of the heater, but lately sometimes it only throws warm air, till I make my first stop, than it gets hot.....all because the heat control valve is hanging up.
Low water in the radiator will also cause a heater to not work.....if the water level is too low to circulate to the heater.
XRM
SOURCE: Heater problems on my 2000 Jeep Grand Cherokee. Please Help!!
THis is a know problem with Jeep GC. If only one side is cold and the other is hot and there are no controls error codes. It is likely a broken temperature blend door on the faulty side (w/ dual controls). Dealer charges a lot to fix ~$800. There is a kit and instructions sold on EBAY to replace the part for $100. Seller claims that a relative novice can fix w/o removing the entire dash board as the dealer does. Has sold hundreds of kits....people seem satisfied....you may check it out. Search Heater Blend Door Jeep on ebay. Replacement parts are aluminum instead of OEM plastic.
Self Diagnostics on HVAC system. Jeep GC has built in diagnostics and will return error codes on the temp display if it is otherwise. Simple to display.
1) Press A/C and Recir button simutaneously
2) Rotate driver temp control knob clockwise then release buttons
3) If no controls error a code of "0" or "00" will be returned.
4) Error codes listings can be found on-line if anything but zero
Dealers charge $45 to run the same check
SOURCE: 98 jeep wrangler no heat
Try this disconnect the heater hoses from the heater core use a hose to backflush the core. Then reconnect and try again.
SOURCE: heater blows cold air
the electric motor that open the heat door looses electrical connection there by the door stays on cold / it is located under the a/c heater assembly / which requires removing the whole dash and heater assy// also bleed all air out of coolant system
there are three doors / 1/ a/c heat 2/ mode /defors 3/ recurculation [email protected]
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