Help! No heat!
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Help! No heat!
I have a 98 Explorer (V6, SOHC, 4WD) and recently replaced the thermostat, water pump and flushed the cooling system. Worked great for a few days, but now don't have any heat. It has automatic temp controls (heat comes on when engine temp warms up) and the blower comes on, but the air never gets warm. Temp gauge working fine - goes to just under 1/2 way after engine warmed up - and I've re-checked the thermostat. Radiator is full and overflow container is full to "cold fill" line with cold engine. Now what??? I'm no mechanic and have no idea where to go from here and don't want to pay the local dealership $175 just to diagnose the problem, so - what should I check next?
Thanks to all.... jw5425
Thanks to all.... jw5425
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From: Las Vegas, NV
First, does your temperature gauge come up to the right level (about half way between C and H) and remain constant after driving a few miles? If so, the thermostat should be fine. If not and remains at C, replace the thermostat again. (You say yours is reading near the middle so go to the next step paragraph.)
If the temp gauge is normal, is hot water flowing through your heat exchanger? Carefully feel the two hoses that provide hot coolant to the cabin. There are two hoses (supply and return) just above the valve cover on the passenger side. If they are too hot to touch, water is flowing. If the water is not flowing, check to see if the valve/actuator will open by applying a vacuum to the control input.
If the water is flowing, check out the "Blend Door Fix" listed at the top of this forum. This is the most likely explanation.
Other possible problems: temp controller module, vacuum hose, selector switches, vacuum actuators, etc.
If the temp gauge is normal, is hot water flowing through your heat exchanger? Carefully feel the two hoses that provide hot coolant to the cabin. There are two hoses (supply and return) just above the valve cover on the passenger side. If they are too hot to touch, water is flowing. If the water is not flowing, check to see if the valve/actuator will open by applying a vacuum to the control input.
If the water is flowing, check out the "Blend Door Fix" listed at the top of this forum. This is the most likely explanation.
Other possible problems: temp controller module, vacuum hose, selector switches, vacuum actuators, etc.
Last edited by LV Dan; Nov 18, 2004 at 03:14 PM.
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Thanks, I appreciate your reply. The hoses are cold, even after the engine's reached operating temp (gauge 1/2 way). Sorry to be so dumb about it, but can you give me details on applying a vacuum to the control input? I do alright taking things apart and putting them back together to replace parts, but don't really know the first thing about the troubleshooting stuff.
Thanks again! jw5425
Thanks again! jw5425
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From: Las Vegas, NV
I would be surprised if the hoses are cold, even after reaching temp. Usually they get quite warm to the touch, even when the heat is off. There might be a plugged port or hose somehwere.
But I would look to the valve that lets the coolant pass through the heat exchanger. It is a device inline with one of the hoses. There should be a small vacuum line connected to the top or bottom of it. You can use you mouth to suck a vacuum on it with difficulty or use a Might-Y-Vac available at auto parts stores for about $40. With a vacuum on it, it should let the hot coolant flow. If not, I would replace that valve.
On rockauto.com, two valves are listed, one with two ports and one with four. I don't know which one you have or what the two additional ports are for.
But I would look to the valve that lets the coolant pass through the heat exchanger. It is a device inline with one of the hoses. There should be a small vacuum line connected to the top or bottom of it. You can use you mouth to suck a vacuum on it with difficulty or use a Might-Y-Vac available at auto parts stores for about $40. With a vacuum on it, it should let the hot coolant flow. If not, I would replace that valve.
On rockauto.com, two valves are listed, one with two ports and one with four. I don't know which one you have or what the two additional ports are for.
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Thanks for the responses. Got a chance to check the vehicle again today - the hoses DO get hot (just takes a little longer than I gave it last night I guess), so I tried the blend door fix. After removing the actuator, I found that by manually moving the blend door to the closed (open?) position, I now have heat. LOTS of heat and no control over the temp setting.... but heat is good, especially in winter in Michigan.
However, after drilling a hole or 3 into the actuator and fitting it with a part of a nail, I could not get the actuator back into the box and as near as I could tell by looking at it in the mirror, the chamber appears to be intact. So I'm guessing that it's the actuator itself that's bad, but I cannot find the part # at any of the parts stores online that I've checked - even FORD.com doesn't recognize the part #.
Does anyone know what the "official" name of this part is? I've tried looking up "acuator", but none of the pictures at the auto parts places look remotely like what I need. The part number on the actuator is F87H-19E616-AB. Thanks for any additional info you can give me.
jw5425
However, after drilling a hole or 3 into the actuator and fitting it with a part of a nail, I could not get the actuator back into the box and as near as I could tell by looking at it in the mirror, the chamber appears to be intact. So I'm guessing that it's the actuator itself that's bad, but I cannot find the part # at any of the parts stores online that I've checked - even FORD.com doesn't recognize the part #.
Does anyone know what the "official" name of this part is? I've tried looking up "acuator", but none of the pictures at the auto parts places look remotely like what I need. The part number on the actuator is F87H-19E616-AB. Thanks for any additional info you can give me.
jw5425
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From: Las Vegas, NV
Motorcraft YH598 (Ford Part Number F5TZ18A318C)
Note that the Defrost, AC, and Heater all use the same actuator with different mechanical arms. The last digit of the Ford number determines: "A" for defrost, "B" for AC and "C" for Heater.
www.rockauto has all three listed under Ford/1998/ 4.0L SHOC (VinE)/Heat & Air Conditioning/ A/C Vacuum Actuator.
Note that the Defrost, AC, and Heater all use the same actuator with different mechanical arms. The last digit of the Ford number determines: "A" for defrost, "B" for AC and "C" for Heater.
www.rockauto has all three listed under Ford/1998/ 4.0L SHOC (VinE)/Heat & Air Conditioning/ A/C Vacuum Actuator.
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Thank for all your help LV Dan!! I must say, I am quite impressed with the friendliness and willingness of people on this board to offer advice without being nasty or sarcastic - keep up the good work and now I know where to ask next time I need help with my truck. Thanks again!
jw5425
jw5425
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Try this
With the actuator removed from the plenum, but still connected electrically, slowly rotate the temp **** and see if the actuator rotates. If it does, you may have to redrill. My first attempt at the blend door fix resulting in my placing the nail too far from the bottom of the actuator. I would drill no more tan a half inch away.
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I did check the actuator after it was removed from the plenum - no motion whatsoever thru the temp range so I took it apart to check the gears. All were fine (no missing teeth, etc) and the end on the solenoid-type thing moved freely also. The only thing I didn't do when I had it apart was test the solenoid, but since the actuator never moved when connected electrically and I was going up and down thru the temp range, I'm guessing the solenoid is most likely the problem. The actuator itself fits snugly into the plenum and opens/closes the blend door without any play, so I don't think that part is broke....... yet. :|
Thanks! jw5425
Thanks! jw5425
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Here's another idea
Before condemning the actuator, check the temperature selector. On my Explorer it's just a potentiometer, subject to wear and electrical failure. One pair of wires should show a resistance change when the dial is moved.
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Sorry, I think the part numbers I gave you are not for the part you are talking about. I listed parts for the VACUUM ACTUATORS. The part number you gave (19E616)should be a good Ford part number.
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Originally Posted by ajguzik
Before condemning the actuator, check the temperature selector. On my Explorer it's just a potentiometer, subject to wear and electrical failure. One pair of wires should show a resistance change when the dial is moved.
And LV Dan - thanks for the update on the part number!
jw5425
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