Jeep liberty no heat

[Kentucky]

Heat works when your moving goes cold if you stop.
Air works when your moving goes hot when you stop
:beatsme

This is in ASAP because it's cold out and my new baby needs heat:wink

[chtucker]

Heat works when your moving goes cold if you stop.
Air works when your moving goes hot when you stop
:beatsme

This is in ASAP because it's cold out and my new baby needs heat:wink

Fan clutch or thermostat?

[Ron's Asphalt]

When you are moving, or when rpm's are raised?

[mmwb]

Is the venting/heating system vacuum actuated? If so, you may have enough of a vacuum leak to prevent a door from opening, but enough at higher rpms. I'm not familiar with that vehicle so call it a blindfolded shot in the dark...

[capeland]

You might need to have the heater core looked at

[capeland]

I also would look at the water pump. When you are moving the pump is pushing and when you are stopped the pump impeller could be bad

[Kentucky]

Fan clutch or thermostat?

Fan clutch seems to work good and the thermostat is new. No over heating or any other problems with coolant. If the clutch was going bad isnt there usually a load squealing noise when turned on?

When you are moving, or when rpm's are raised?

I guess I would say when the rpms are raised, but if your coasting down the street it also works fine. Come to a stop light and three to five seconds later heat / or air goes cold or warm.

I also would look at the water pump. When you are moving the pump is pushing and when you are stopped the pump impeller could be bad

wouldnt this cause the car to overheat?

[Ron's Asphalt]

Coasting down a hill, your rps's will still be raised above idle. I do not know Jeeps very well, but you are dealing with a low flow condition. Could be a restricted heater core, could be a water pump problem. How many miles are on this? Also, you say the A/C goes warm when you stop? This is an almost completely different system from heat.

[Kentucky]

02 jeep liberty 110,000 wife miles;).

Yes the air conditioner blows as cold as it can till you stop then it blows warm. Start going again and it goes back to nice and cold.

start the car in the driveway and put the heat on and it gets a touch warmer (enough to defrost the windows only). Pull out of the driveway and it blows hot. Get to the stop sign at the end of the street and stop(400yds) then it goes back to cold air blowing out.

I could see this as being two seperate issues, it's just kinda weird they are doing the same thing.

Has a brand new radiator and thermostat and has been preasure tested.

[wingplow]

i know on my wrangler if the coolant level is absolutely full it'll
blow not quite as warm at an idle...not to sure about the Liberty's

[JD PLOWER]

I would check the simplest thing first, coolant level. Is it full? Is the mixture proper? Just some thoughts...

[Plow Dak]

lots of good answers and every one could be a cause.

Check for full coolant.
Make sure engine comes up to operating temp.

On cold start do NOT turn on heater blower motor. Open hood and locate heater hoses. be careful and begin feel the hoses going in and out.
The hoses should warm up about equally. If one is a lot hotter than the other then i would go after a restricted heater core. If they are both kinda cool and then both warm up with higher rpms then i would go after a water pump as a initial guess. This is where I would start. I believe there may be some vac control stuff around there too as i have not been into a liberty very much but i would start there.
True story
Had my old truck and my dak now doing the SAME thing. AFTER i changed the water pump i have lost idle heat. In my old truck i changed the pump again and solved it. In my dak i've been to dam lazy to do it. i drive 5 miles to work so to be honest it wouldn't help me much. It's possible you have lost your impeller but try what i suggested to at least get you to eliminate some things.
For some reason if both heater hoses are hot and you turn on your heater and one turns much colder and no heat then your looking at blend doors etc.

just some food for thought

[Ron's Asphalt]

Good diagnosis for restricted heater core there.

[PRR]

> Come to a stop light and three to five seconds later heat / or air goes cold or warm.

Pump, core, fan, etc take more than a few seconds to go hot/cold.

I think mmwb has the clue. I don't know the vehicle, but a lot of cars use vacuum gizmos to work the many doors and valves in the heater. These will typically swing in a few seconds.

Also they typically have a vacuum reservoir to hold vacuum when you OPEN the throttle and vacuum vanishes. On a 1966 Galaxie this was a #10 bean-can on an inner fender; 1979 T-Burd (also vacuum headlights) had a neat pressed tank. There's a 1-way valve in the line from the manifold. There's a lot of old cheap rubber hose. All that should be examined. Much of it may be hard to find or see.

If you can reproduce the fault with your head under the dash (maybe race/slack the engine in neutral?) you may hear hisses and creaks as the valves do their things (or not).

Good Luck. I think on the T-Burd I finally wire-tied the hot/cold flapper to HOT fall to spring and let it go at that.

[PRR]

> Come to a stop light and three to five seconds later heat / or air goes cold or warm.

Another thought:

Has anybody touched the vacuum hoses?

There's TWO sources of vacuum: manifold vacuum and "ported vacuum".

Manifold vacuum is related to lack of hard load and is typically strong except when working hard (mash the pedal, or lug hard in higher gear). With reservoir to hold over short times of hard-work, manifold vacuum is mostly strong.

Ported vacuum comes from the edge of the throttle plate, inside carb or throttle-body. Above idle it is the same as manifold vacuum. But when the throttle comes down to the idle-stop, it shifts to full air, zero vacuum. This is only used to control ignition advance: related to load when off-idle, but no-advance when at-idle.

If someone has plumbed the heater vacuum controls to ported advance (AND you have leaky reservoir or hoses) then "come to a stop light" (drop to idle) will kill vacuum to heater flapper motors and they typically flop in a few seconds.

Moreover if hoses are swapped and ignition advance is seeing manifold vacuum, your idle conditions are wrong. Typically idle is way-fast. If the hoses were swapped as part of a larger tune-up, this would be corrected ("Gee, those new plugs made a big difference!"). So if that may have happened, it may take more than a re-swap to get everything right again