No heat?

only way to find out is feel the heater core hoses.

cold or warm heater core hoses possible plugged core, air in lines or bad heater control valve if equipped.

This guide can help us fix it

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

if theres a difference in temps between hoses could be a bad/plugged heater core, air in lines or plugged lines.

if both hoses are hot its in the dash.

Heater problem
1999 Mercury Mountaineer V8 Automatic

We have replaced the coolant and the thermostat but still have no heat in this vehicle. It blows cold air only. Can you suggest what else we should look at?

With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If they are..........

The temperature is controlled by the use of an air mix door that is operated by an electric motor/actuator. This door can be jammed or the actuator can be inoperative or have stripped plastic gears internally.

Heater problem
1999 Mercury Mountaineer V8 Two Wheel Drive Automatic

I turn my heater on it only blow cold air , no heat. what could cause this to happen?

Hi:
First, is the engine warming to a normal operating temp? Second, with the engine running, hot, and the heat on, feel both heater core hoses. They should both be hot. Finally, is the coolant level full?

Let me know what you find. IF these things are all ok, we will need to look at the blender door.

Joe

I had my heater core replaced. Now when I turn heater on it only blows from defroster even when I have the setting on floor

take it back to the people that fixed the heater core or you can do this yourself. check to see why mode door isn't getting vacuum as it may be disconnected or a hole in line from heater core replacement.

ok thank you

no heat....ballpark figure for fixing

first do soem stuff yourself, see if both hoses leading to heater are hot it could be no vacuum to water valve on engine. check for a vacuum leak and check to see if vacuum motors on heater are getting vacuum or are working if they are. then you need to go from there. pic enclosed on lh side.

Heater problem
1997 Mercury Mountaineer V8 All Wheel Drive Automatic 190k miles

After letting my truck warm up this morning I got in and turned the heat off because it was insanely hot, and after I got about ten minutes down the road it cooled off enough to turn it back on and when I did it worked for about 30 seconds and went to cold air. I believe it was just blowing outside air because my a/c has been torn up since last summer so it obviously wasn't a/c air coming out. After the heat went out I noticed a soft, constant clicking coming from what seemed like deep in the dash just to the right of my steering wheel, but it very well could have been coming from under the hood, it was hard to tell. This clicking noise goes whether the heater is on or off, constantly as long as the car is running. My first thought was thermostat but I drove the truck for 3 hours after that happened without stopping and the engine temp never fluctuated so now I'm thinking it may be my heater control valve. Does this sound like a decent assumption? If so is there a way to tell if it is bad by just looking at it? I'd hate to buy one and put it in for nothing. Any info would be much appreciated, if you think it could be something else please let me know. Thanks in advance for any advice.

EDIT:
There is a possibility this clicking noise was present before the heat went out, but I didn't notice it if that was the case.

It sounds like the blend door is stuck. It is what determines if you get AC or heat. It is under the dash and half of the dash needs to be removed to access it. That is my first guess based on your discription.

Let me know what you find.
Joe

I turned the heater on one morning and was working fine. The next day I turned it on and it was blowing cold air. I have replaced the thermostat and still won't blow out hot air. Fan works fine. A hose was also replaced due to wear on hose. Still won't work. I can't figure out what is wrong, could it be the core in some way and how would I know that is the problem

Do the heater hoses get hot? Does the engine reach normal operating temp? Another possibility is an actuator under the dash.

Just to add, if both heater hoses are hot, I don't think it is the heater core. You could flush the heater core if you wanted?

Heater problem
1997 Mercury Mountaineer V8 Four Wheel Drive Automatic 125k miles

1997 Mercury Mountaineer, Heat problem. Occassionally a delayed flapper could be heard opening from underneath the dash and then the blower would come on. The Blower had only worked on high speed setting. Now Nothing! No Blower, No Flapper noise. No Heat At All. Any Cure?
It appears to me the blower motor is controlled by the flapper opening. Sometimes the rear heat will blow warm without the front blower actually operating.

When your blower motor was working in only one speed "High". It is very possible your blower motor resistor is either stuck or needs replacement. If you can repair it yourself that will save you some money. Here is what you need to do. Remove the speed control servo. Disconnect the electrical connector.(1) Remove the bolt. (2) Position the speed control servo (3) aside.

Remove the coolant/washer reservoir. Remove the two screws and the two nuts. (1) Move the coolant/washer reservoir (2) aside.

Refer to the sketch below for the blower motor resistor location. You will see the blower motor resistor (1) just below the vent hose. The arrow is pointing at the blower motor housing. Turn the heater fan speed selector on "High". Turn the ignition "On" but do not start the engine. Get a long screwdriver or something similar and place it against the resistor housing. Give the resistor a slight tap, listen to see if the blower motor is working. If it isn't, give it another tap.If it is not working, give it one final tap. If the blower motor is still not working the resistor needs to be replaced. To remove the resistor: Disconnect the electrical connector from the resistor. Remove the two small bolts. Remove the resistor and replace it with a good one. You can buy the resistor "new" at an automotive parts store or if you have a "Junk Yard" or "Auto Salvage Yard" near you, you can pick a used resistor up from them and save some money

I hope that helped you out; Rick

Thank you Rick for your detailed response. I had to run to the junk yard to grab a three knob controll for inside the vehicle because I had broken one of the knobs, As I was there I did grab a resistor from that vehicle and installed it. The problem continues! No Fan. So, I ran a wire from the battery to the blower motor as it was in place and spliced into the positive wire of the blower to see if the blower would work. The blower works. (high Speed of Course)
Some where between the inside fan control and the blower I've lost power to the blower. I followed the blower motor wire to the frame of the vehicle to a black box with three or four contacts inside, which is located on the passenger side closer to the front of the vehicles frame. Could my problem be locate in this black box? and would the resistor I replaced it with be bad too?

As I said I spliced into the blower motor wire from the battery and the blower can be controled from off to on (high speed) from inside the vehicle. I naturally want to control all the speeds and I'm still looking for a solution to the blower not responding to the setting inside the vehicle. As I mentioned before I believe, the blower does not operate on any speed that was set inside the vehicle. It use to work only on high speed before, it stopped working completely.

Fuses inside have been checked

Thank you in advance for your help and expertise!!!

Hi rjmillsbjkl ; The problem "possibly could" be in that black box. The resistor is usually always the case 9:1. There just might be "very slight" chance of (1 out of 9) you did pull a bad relay out at the junk yard. You mentioned that you grabbed a three knob control so you "do" have the correct resistor that goes with that configuration. Some mountaineers have a digital "EATC" (Electronic Automatic Temperature Control) and the resistors electrical connector is a little different than the knob type. I'm thinking the electrical connector may be giving you a problem but not sure... The (resistor you took out of the junk yard)... is it identical to the one you replaced ? It is now narrowed down to the resistor/ wiring harness/ black box. We have not ruled out the blower motor completely but we should throw that in too just in case.

Just giggle electrical connector (2) in the sketch above and see what happens.... I will be back later on today. Rick

I have a 1997 Mercury 95000 miles it has no heat,and also shows no engine temp on the dash I have replaced the coolant temp sensor. thermostat and checked the coolant level in the radiator.The blower works properly and Both hoses that go to the heater are hot what next?

Both hoses hot would indicate that the heater core is getting the heat it needs to supply the need. This sounds like either one hose is hot and the other warm meaning a plugged core or a malfunctioning heating system, ie flap not opening whether mechanically controlled or electronically.

[quote:204427a53f="Bruce Hunt"]Both hoses hot would indicate that the heater core is getting the heat it needs to supply the need. This sounds like either one hose is hot and the other warm meaning a plugged core or a malfunctioning heating system, ie flap not opening whether mechanically controlled or electronically.[/quote:204427a53f]

If the heater core was plugged wouldnt it blow warm?

my heater works but on blows out at a low setting weather in set it to high or low but my rear one works just fine

Can you please rephrase your question?

when i turn on the heater it blows out as if it is on the lows setting when i turn it up it still blows out low. my rear unit blows out high and low.

while i drive the faster i go it seems to blow out a little faster but really no change. i can only feel it when i put my hands on the vent.

The air flow is low. If the blower motor noise changes when setting is increased it means air restriction in the air flow circuit. Check the cabin filter if equipped.

Hello, I recently took my truck to the shop because the heater would take a very long time to heat up (about 15 minutes of driving) and my wife said it never heated up on a 45-minute trip she had last week. The shop checked for a coolant leak (as advised by a company that changed my oil) and found there was too much coolant so they removed some. Then they test drove the vehicle and said that it seemed to be working fine and it got lots of heat within 6 minutes. The next two days it surely did work. However, it then reverted back to doing the same thing, the thermometer gauge seems to indicate the vehicle is getting to operating temp but is still not heating. Thermostat needs replaced? Blend door getting stuck?

Thanks

Hi ljh2100,

Thank you for the donation.

Perform the following test first.

Check for proper coolant level.
Start engine and turn heater ON.
When engine reaches normal operating temperature, feel heater outlet hose.
It should be hot.
If not heater core may have an air pocket, heater core may be plugged, or thermostat may not be working
properly.

If outlet hose is hot, then problem should be due to blend door.

i will check now and see if that is the problem thanks for the response

Where is the heater outlet hose located? The truck is not here right now but what is involved with fixing the blend door if that is the case?

no cabin air filter. the noise cant tell any different

The picture shows the heater hose which have been disconnected.

If it is a broken blend door, which is quite common, it can be replaced from under the heater hoses. Normal procedures requires the dash to be removed but some of the guys out there have done it without doing so.

Tip: Broken blend door replacement short cut You can purchase the door seperately from Napa(part# BK660-1810) and replace it from under the hood. All you have to do is split the evap case and remove cover, evaporator and accumulator from vehicle to gain access to the hole in firewall so you can get to the door. Next, drop the glove box and disconnect the actuator and get it out of the way so the door will come out. With a small pry bar, gently pry down on the top of the door as close to the pivot point as you can and door will come free. The next thing to do is break or cut the door in half so it will pop right out. If you choose not to do this, you can get it out, but it is a little tricky. Now take the new door and cut a small section off the bottom of door   to make installation easier(it will still seal inside case). Start cut 3/8" up from bottom on outer edge and taper down toward bottom edge about 2" from the outer edge. Then put in through the firewall hole and into place. This is a little tricky also, but can be done, do not get frustrated. It will take the same gently prying with the pry bar to get pivot hinge to seat in hole. Reinstall actuator, evaporator, and accumulator and recharge and you are done. After you do a few, you'll be doing them in about 2-3 hours.

Since the blower fan motor is not responding to the control, it could be a failing fan motor, a fault with the blower motor switch controller.

Is your HVAC system manual or automatic?

How long does a blend door take a mechanic to replace? To me it seems like that would be the most likely scenario given the fact that the heater components do seem to be in working order but I assume the thermostat could be be the issue.

not sure, i tested my power to the blower and it is getting power if that helps.

Based on the procedures described it would take about 3 hours. Removal of the dash and heater housing would take much longer.

If the heater hoses are not as hot as they should be, then it could be a faulty thermostat.

Automatic means the control panel has a function for Auto.

Seems the notification has a problem and I am not being nootified of any replies.

Heater problem
1999 Mercury Mountaineer 6 cyl Four Wheel Drive Automatic 87K miles

The Air from the heater stopped blowing out of the front vents on the dash board and the defroster vents. it works and blows hot air for the back seat vents and the rear window defroster.

check fuses
suspect front blower motor