My heater is not working why?

It sounds like the temperature blend door actuator is not working but to be sure this guide can help https://www.2carpros.com/articles/car-heater-not-working check the heater actuators they may be stuck it will be similar to the pictures i'm sending. they are listed as #1 & 2 they move to switch the air in theheater box. They may have vacuum hoses going to them as the picture i'm sending is electric...

I can't get the heat to work on my vehicle. The fan blows great, a/c works great, only cool air comes out when heater is on, will not heat up at all. No smells, just clean cool air.

My jimmy did that 2 years ago. Its a 2000 and one shop told me I needed to replace the Heater core. I took it in to a shop that works on the radiator and told me it was clogged up with radiator fluid. They did a huge flush. They said the made a special tool. They seen so many jimmy's with this problem and they fixed it. A huge flush cost me 300 and worth it. A new heater core is almost 1000. Try a deep flush. Maybe a radiator expert shop.

When I turn on the heat it only blows cold air.I have changed the thermostat and flushed the coolant. My brother doesn't think it's the heater core. What else could it be? Some kind of switch or relay?

first feel the heater core hoses where they go into the firewall right by the fire wall, if one is hot and the other isnt it needs to be flushed, if both are hot then you may want to check your blend door under the dash, and if neither his hot then you should check the coolant flow valve, you will find it tied into the heater core hoses.

took it to a well respected service man just for diagnoses. no heat..he says it is the controls or damper motor in duct work. i swaped out controls with my sons s 10 and it still wont produce heat...must it be damper motor? if so how easy is it to get to?

did the shop check the heater core? heater cores sometimes get clogged

checked hot to cold damper and it works, going to flush system...the repairman felt the hoses going into the heater core and seemed to be hot to both of us,but was not as hot as the top radiator hose.going to add flush to entire system,...is that the best way to go?

yes that sounds like the best course of action

plugged it was, but i must say it was the cleanest radiator i ever drained and flushed...it fooled me...thanks jeep

no nproblem

The heater produces heat and the blower works on all speeds. No heat flow is going to the floor when the control is in the floor or blend position for floor and defrost. Instead flow is defaulted to the dash vents only. The defrost only position works. I have visually inspected the control switch and vacuum tubes in the dash. They appear in good shape. Is this a common problem? What is the best (easiest if possible) way to diagnose what is going on?

if you feel under the dash there shold be a vacuum motor that does the moving to blend or defrost.etc, see if that is getting vacuum and if not go back to the contro l head and unplug it to see if it is. it may be leaking at the control head or the manifold wher eit picks up the vacuum on theengine.

I have had the radiator replaced, the heater core replaced and the heating system flushed, and when I switch it to the heater, I still get cold air. What else can I do?

Did you replaced the thermostat? could also be a heater control valve/air mix and blend door actuators/vacuum problems. or a problem with the air temperature control system

Heater problem
2000 GMC Jimmy 6 cyl Four Wheel Drive Automatic

i replaced my t-stat because i was not getting heat in my passenger compartment. Now it only heats intermittently. i t seems as soon as i put a load on, the heat comes, when I idle the heat goes away...any ideas??

Vacuum leak to the control head for the heater. Look for a line that goes through the firewall and follow it to the engine. Cracks or loose connections could be leaking.

my heater won't change from vent to floor to defrost. so i looked at the vacume lines and they have oil in them. Could it be that the vacuum actuator switch on the transfer case is no good, assuming that where all my vacuem connect to???

no, the vacuum connects to the motor. do you have vacuum to the control head?

This guide can help

https://www.2carpros.com/articles/car-heater-not-working

Roy

My heater is blowing out cold air, i am trying to figure out if its the heating controls or the hot cold flapper (cold hot dock, or vacuum actuator). How do figure out what the problem is between those two. I have already canceled out, coolant, thermostat, water pump, and the heatig core.

Do you live in an extremely cold region? Does the engine reach normal operating temp? What is your normal operating temp in degrees F? Do the heater hoses get hot? You might check for applicable hvac trouble codes. Some of the national brand autostores check codes for free.
If a temp door under the dash is having a problem, I'd have to get under the dash and check it out.

Heater problem
1998 GMC Jimmy 6 cyl Four Wheel Drive Automatic

I am having a problem with my heater which has an automatic temp control and it isn't really working. It either blows really hot air or none at all. The air conditioner doesn't work now, either. Chevy garage said it is the automatic temp control auctuator or something else. He wants over $1,000.00 to fix it. I can't afford that, so has anyone else had this same problem and know for sure what is wrong? One person said it is probably the blending door. If it is one of these, how do you know where they are and what do they look like? Please help! Thanks in advance, brasshorse

blending door is behind glove box(small release top left, bend down spring loaded tab then lower glove box.) door is on right. plastic gear can sometimes break. can epoxy or replace or could be vacuum line has leak. check vacuum first by disconnecting line and turn your climate knob from cold to hot(or vise versa) if you feel vacuum on your thumb then probably your gear

Im only getting high heat out of car vents no matter what I select on climate control selector. A/C works but its just not blowing cold air into vehicle. On heat selection, I cannot control heat either. Could it be blend-door broken or stuck in heat mode, or the blend-door motor failed, or climate control selector failed?

This sounds like the temperature door actuator is not working. I would remove the actuator and try moving the pivot for the door by hand here is a guide to help you see what I am talking about.

https://www.2carpros.com/articles/replace-blend-door-motor

Here is the location on your car.

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

Cheers

My a/c was recharged and the system is working normal. My problem is I select max ac cold and it blows as is the heater is on. Also even if I select just vent ac turned to cold position is still should suck outside air and blow somewhat cold but still dont. It all blows hot air. So ac system is charged right and heater is working properly so why does it blow hot when I turn it to ac vent or max ac?

I have the same vehicle, and the same problem. I'm going to replace or fix the temperature selector switch, which controls the damper door. May have to replace the whole hvac control assembly and or the damper door. While there I replace the heater core, hopefully I won't have to go in to the dash, wish me luck!

Heater problem
1996 GMC Jimmy 6 cyl Four Wheel Drive Automatic

Temperature gauge only seems to go to 160 even after installing a new thermostat. Heat is only luke warm at best. Is there any other valve in the system that controls coolant to the heater core? Is the engine temp not high enough and what else can we look for besides the thermostat?
The engine was replaced this summer, and the heat worked great last winter.

What is the new thermostat rated at? The factory unit is 195 degrees. I would measure the actual coolant temp with a mechanical gauge to see if it is actually heating up. Also check to see if your fan clutch is operating. If it is locked up the extra airflow over the radiator could be causing it to stay cool. With the engine off you should be able to move the fan, if you cannot the clutch may be bad.

I have changed the thermostat and it is still not operating at normal engine temp - it runs cool. I have no heat but the vents work fine at all levels. Any suggestions?

Try warming the Vehicle, then carefully feel the heater hoses, are they both hot? If one is cooler than the other, You need to flush the core, or do a replacement job on the heater core. Also if the system has a heat control valve on the heater hose, make sure it is working! Also check the thermostat, and the temperature blend door, thats under the dash, in the heater plenum...You can flush this yourself, buy the prestone flush kit and install the tee in the heater return line. Disconnect the heater hose at the waterpump, clamp the hose in back of the tee you installed and back flush till it runs clear...20 mins or so. As far as running cool is it a low reading on the gauge? or have you used a thermometer in the radiator?

Hello everyone.I recently purchased a jimmy and i spoke to the previous owner and said there was nothing wrong with it except that it has no heater and i would have to replace the heater core and so i did....i got nothing.I did some research and found that the heater cores tubes are supposed to be connected to either the engine or the radiator in order for anti freeze to enter into the core to transfer heat.I realized that the guy just had one hose runnin from one of the core tubes(larger opening) directly into nothing,so its not plugged into anything and the other one doesnt even have a hose.I checked the control valve and everything looks under control.Im not sure if my heater blower is working like it is but i get a feeling that isnt my problem right now so im trying to focus on this situation of the dangling hose.If you can please tell me where that hose(connected to one of the core's tubes) goes.Is there supposed to be a hose connected to something from each of the core's tubes?

The heater core should have two pipes coming from the firewall. Both should have a hose attached to them. One is the supply line and the other is a return hose. One will come from the waterpump and the other goes (I believe to the intake).