Jeep Grand Cherokee NO HEAT

[SouthernMNFisher]

I have a 01 Grand Cherokee with the inline 6 with 74k miles on it. I recently had to replace the coolant pump. Now there is a lack of heat. I filled it with antifreeze. I also did a cold start and took the radiator cap off so the antifreeze would suck down, however nothing sucked down so im assuming it is full. I tried this to see if i couldnt pressurize it better. Mistake?

When I start it in below zero temps the temp gauge goes about half away with in 5 minutes. I am assuming that is not normal. Could it be a bad thermostat or could it just be sticking?

Warm air does come out but it isn't enough to warm up the inside of the vehicle.

Any help or ideas would be greatly appreciated.

Thank you in advance

[Walleyehooker]

Sounds like your thermostat isn't opening up.

[Jeremy airjer W]

Sounds like your thermostat isn't opening up.

If the thermostat where not opening there would be all kinds of heat but the engine would also likely overheat. The only time the thermostat will affect the heater is when it is stuck open. When this happens the temp gauge will read lower than normal while driving and may read more normal when at idle.

I'm betting you still have air in the system. Purging requires the removal of the radiator cap and idling the vehicle until completely warmed up. Topping off the coolant as necessary. Once the vehicle is up to operating temp snapping the throttle several time will help push the air out of the heater core. Continue to snap occasionally and top off the coolant and heat will return.

[Jeremy airjer W]

I should ask, was there heat before you replaced the water pump?

[SouthernMNFisher]

Jeremy

I recently bought the vehicle and it was inside being stored. So the dealership really wouldnt have known. I got a great deal on the Jeep after I had them replace the pump and rear axle seals. So I really dont want to bug them with this unless I can not fix it on my own.

[Macgyver55]

I'm wondering the same thing as Jer, did you replace the pump to fix this problem or did it just do it after you put in the pump?

It could be coincidence but it sounds like it could be the dreaded Jeep blend door problem.

I've done a couple of these the "easy way" and it works well.

http://www.jgcparts.com/JGCParts_Jeep_heatertreater_International.html

[SouthernMNFisher]

I'm wondering the same thing as Jer, did you replace the pump to fix this problem or did it just do it after you put in the pump?

It could be coincidence but it sounds like it could be the dreaded Jeep blend door problem.

I've done a couple of these the "easy way" and it works well.

http://www.jgcparts.com/JGCParts_Jeep_heatertreater_International.html

I have never heard of the blend door problem.

I replaced the pump because it was leaking. The pump was shot

[SouthernMNFisher]

I checked out the link. That is interesting. I think i ran into your video online as well. I will try and see what the code is that pops up. When I switch from defrost to panel everything seems to kick in correctly but i am not 100% sure

[Jeremy airjer W]

When I switch from defrost to panel everything seems to kick in correctly but i am not 100% sure

That is the mode door. The mode door switched from floor, vent, defrost. The blend door is the part that switches from hot to cold.

With the fan on full blast and the mode set to vent you should hear a distinct difference in the sound from the vents as you switch from full hot to full cold. If you do not hear a sound change than you could have a blend door issue.

[Macgyver55]

I checked out the link. That is interesting. I think i ran into your video online as well.

Not sure what video you mean, but I should also add that I am not promoting the product in the link, just using the pictures to show you what is involved.

[Jeremy airjer W]

One other thing. With the engine up to temp see if the heater hoses are hot. They should be relatively the same temp. If one is hot and one is cold than there is an issue with the heater core. if there both warm than there is not enough coolant getting to the heater core. If they are both hot than there is an issue with the blend doors. Granted there is a little experience needed in order to determine the relativity of hot, warm, and cold, but you get the idea.

[SouthernMNFisher]

one more small tidbit that might be helpful... When I have the heat on defrost and have it at medium or lower blowing power the air feels warmer. When I turn it on full blast it tends to get cooler... If that helps any diagnosis at all...

[Jeremy airjer W]

The heater core is a heat exchanger. cold air passes through the heater core and is warmed by the coolant inside. If the flow of coolant is limited to the heater core than there will not be enough heat transferred to the air passing through it. with the blower on low the heat requirement of the coolant is less. With the blower set to high the heat demand is at its fullest.

[SouthernMNFisher]

The heater core is a heat exchanger. cold air passes through the heater core and is warmed by the coolant inside. If the flow of coolant is limited to the heater core than there will not be enough heat transferred to the air passing through it. with the blower on low the heat requirement of the coolant is less. With the blower set to high the heat demand is at its fullest.

So it is probably a coolant issue? Not enough pressure? I noticed when they replaced the pump they didnt add any extra coolant to the reservoir tank... How would you go about pressurizing it? I noticed a reply earlier that might work.

Any other advice?

[expl]

Possibly air bubbles in the system.Fill the radiator and resivoir full.start the truck and park it on a hill with the radiator up hill,take the cap off and let it run it with the heater on high,revv it up to a couple thousand rpm.for a few minutes here and ther.if the temp guage never rises or sucks down your coolant level after 20 minutes it could be your thermostat stuck open,or it could be you got a halfway working new pump.ive seen it happen.if it wont take anymore coolant its more then likely the thermostat is stuck open tho.

[SouthernMNFisher]

Possibly air bubbles in the system.Fill the radiator and resivoir full.start the truck and park it on a hill with the radiator up hill,take the cap off and let it run it with the heater on high,revv it up to a couple thousand rpm.for a few minutes here and ther.if the temp guage never rises or sucks down your coolant level after 20 minutes it could be your thermostat stuck open,or it could be you got a halfway working new pump.ive seen it happen.if it wont take anymore coolant its more then likely the thermostat is stuck open tho.

I took the radiator cap off and started the jeep cold. Let it run for about 2 minutes then hit the gas to about 3-4000 rpms a couple of times. I could see the coolant at the brim of the cap. It is as full as it will get. I couldnt tell if anything was being sucked down.

Like I mentioned before the engine temp gauge will go about half way with in 5 minutes of the jeep running and it is -15 degrees out right now. That doesnt seem normal which makes me think its the thermostat? It sucks its so cold out and I dont have a garage to pull it into to work on it.

[expl]

I hear ya on the cold part,If the guage is up to half way and your not getting any heat and the system isnt sucking anymore coolant in put a new t-stat in it,pretty sure thats your problem its cheap and I dont know about a jeep but it shouldnt be to hard to do.It took me twenty minutes tops on a ford truck last week.good luck having no heat sucks seems lkke every vehicle ive owned has had this issue at on time or the other.

[Jeremy airjer W]

So it is probably a coolant issue? Not enough pressure? I noticed when they replaced the pump they didnt add any extra coolant to the reservoir tank... How would you go about pressurizing it? I noticed a reply earlier that might work.

Any other advice?

It's not a pressure issue, it's a flow issue. Air pockets act like road blocks for coolant. If there is air in the heater core than it needs to be burped. I gave you the procedure in a previous post. That is the way it is done 99% of the time. It needs to be done anytime a component of the cooling system is replaced whether it's a radiator, thermostat, water pump, hoses, heater cores, housings, frost plugs, head gaskets, intake manifolds, etc. if it is not done the first thing that is usually noticed, especially in winter, is no heat, since the heater core is typically the highest mounted part of the cooling system it is usually the first to show signs of low coolant level.

If you are sure there are no air pockets, and you are sure the blend doors are working, than there is a possibility that the heater core is plugged. It has been a good winter for them. I have been unplugging 2-3 a week minimum for the last few weeks.

[Jeremy airjer W]

It needs to run longer than two minutes especially outside in the cold. At minimum with the engine running at idle it will take 20-30 minutes.

More coolant will not be sucked in until the thermostat opens. You can tell when this happens by feeling the upper hose near the radiator. When it gets hot the thermostat has opened. This is the time to raise the RPMs and snap the throttle. The air in the engine can't make its way out until the thermostat opens.

[SouthernMNFisher]

OK I will give that a try! I really appreciate all of the suggestions and input! I think I have a good base to test some things on. You guys are awesome! Thanks!

[1968]

To aid in burping the system a "spill free funnel" works great. They are usually under $30 and works on just about every domestic and asian car.

With the key on, engine and blower off you should be able to hear the door moving when you operate the controls. It's subtle, but you can usually hear if an air door is hitting it's stops. Sometimes the actuator can even be seen by looking under the dash or removing the glove box. The hub in the actuator that turns the door is often visible from the outside. If not, remove it and manually swing the door to make sure it isn't broke. At that point you can also see the business side of the actuator. Change temps and see if it rotates(typically only about a quarter turn.

[trollingforeyes]

One no cost thing that can be tried is to warm up the car and set the heater to high temp. Now if one of the heater hoses is hot and the other cold it is possible that there is an air lock in the heater core. This can be eliminating by removing the cold hose from the heater core tube while the engine is running. You do not have to completely remove it, just show a small space between the tube and hose to let any air expel from the system. If you have coolant flowing at this point and both hoses are hot, then you have to look at the blend doors.