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Performance Upgrades - Maintenance - Modifications - Problem Solving - Off-Road - Street Trucks. Covering the Explorer, ST, Sport, Lincoln Aviator, Sport Trac, Mercury Mountaineer, Mazda Navajo, Ford Ranger, Mazda Pickups, and the Aerostar. Featuring H.I. - Human Intelligence.
Working on a friend's Explorer (a '94).
Blower fan works at all 3 speeds.
No heat what so ever.
Current outside temps are in the teens and she has to drive 1hr. for work.
Where do I start?
A bad/plugged heater core maybe?
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Fill up coolant. Check lines like stated above. You could always try and pull the heater core and flush that first, then do a full radiator flush next if needed.
If I recall correctly, there was a part installed on 94's that would cut off the water flow through the heater core when the "Max A/C" was initialized, it was a vacuum controlled "switch" installed on the water/coolant lines going to the heater core. This may have gotten stuck in the "closed" position, so make sure there's flow to the heater core first. Then go from there.
let the vehicle get warm, feel the hoses to the heater core. If one is cold, back flush through that one. You don't have to pull the heater core to flush it.
You might also check the hoses to make sure they aren't coming part inside and blocking flow
Look for a failed heater hot water valve like Josh suggested is possible.
Next check for vacuum to the heater assembly vacuum pots. Some times the vac hose going thru the firewall will just come off.
Last is the dreaded blend door problem. Is any air at all moving with the fan on? To the floor, the defroster, the panel vents?
She's been having coolant leakage issues and she's been trying to keep it topped off with water to prevent over-heating. I'm thinking a cracked radiator but haven't had the chance to diagnose it yet. I believe she is planning on having a new radiator put in this week.
There is airflow coming from any vent position selected, just no heat. I'll impliment these diagnosing tips as soon as I get the chance.
...this is what she gets for buying an $800 beater.
Looking into the issue I have found several problems in my situation. A pinhole in the radiator, actually I think there are two, but for sure one.
Second, I have my coolant gauge all over the place, but mostly in the space just before N to O. Grabbing the top rad hose it is really cool compared to the bottom hose. The heater hose lines are warm, but not so much. Possibly a weak h2o pump. Having recently, this summer, flushed the coolant system, I figured it was time to do it right, like Doonze since I suspect slimy gunk still in the system. So while the rad is ordered, I am reflushing the heater core, replacing the stat, coolant sensors and checking the fresh air flap in the heater box.
I have 127,000 miles and several things have never been replaced so a little TLC and a few dollars will take her on until a rebuild...I hope. She runs really quite well, despite some issues now and again, and she starts up every time.
I'm having same issues! I have a 91 and installed 3 new t-stats, all new hoses, heater core and am still having weak heat. I vacuum filled with tool so I beleive there is no air in the system. My temp gauge hangs right around "N" in normal. I know these are characteristics of air in system, but am lost. I thought maybe the coolant is bypasses t-stat some how and not allowing coolant to get warm but can not find any bypasses on AllDataPro.com
I still think it is scum in the radiator and doing Doonzes super-flush is the cure.
I saw a Ford recall thing about that bypass dodad. I don't know where I found it on the web, but I wish I bookmarked it when I saw it. Sounds plausible.
You might be getting an air leak in the cooling system. Since everything is new in your cooling system except the pump and radiator, those are the next things to check.
I never thought my radiator was a problem until I was in 5 degree weather 2 weeks ago and I noticed I was steaming a little bit after idling for a few minutes. I popped the hood and it was not coming from the the cap, but a pinhole in the radiator, 2 inches from the hot side hose and the plastic end caps. Until the engine comes up into the normal range, it behaves just fine. I have an e-fan using an thermo mounted on the radiator and it never comes on anymore, it did during the summer. All this started happening in November after I did a basic 15 minute radiator flush with Prestones coolant flush stuff. So, in my case I am sure it is loose junk floating around.
First off there has to be heat in the system (gauge into the normal range anywhere is fine)
Make sure somebody didn't bypass the heater core cause it was leaking... The heater control valve is attached right there by the firewall. Both lines from the core and engine go to the sides of it, and there is a small vacuum line on the bottom.
When you put the heater control on any position except for off or Max A/C it will let the vacuum motor move the valve so that coolant can flow. Ford added this feature when people were complaining about poor Max A/C performance on the early models.
Check that the vacuum motor is moving when the position of the control is changed. Obviously if this is not working you will not have flow to the heater.
You can connect a garden hose to the heater core and flush it out both ways. If it's leaking its easy to change, there is an access panel under the dash.
that heater control would be an under hood item, right? My 91 doesn't have one.
after replacing 3 T-stats it's time to get get more specific. Tstat's should be closed at room temp, then put one in a pan of water in the stove, it should open right before boiling is reached. A candy thermometer would help. You aren't putting them in upside down are you? Can that even be done?
After 3 T-stat's it also time to suspect the sending unit on the gauge. Get a temp taken with an infrared scan tool or check the resistance of the sender.
About the only thing that can make a motor run cool is the T-stat stuck open or be missing. Even the fan running all the time won't do it because the t-sat will close.
Other things can happen to cause no heat in the cabin like a blown head gasket where the water disappears = no coolant flowing to transfer heat.
You could have a weak sending unit giving a low reading & a blend door problem while the motor temp is actually fine
You know, I don't get that burping thing for these explorers. I've had my cooling system open and drained well many times. When the tstat opens any air is gonna move to the top of the radiator.
When it all cools back down the vacuum created by cooling pulls coolant from the overflow into the motor. Or wait till the motor is cool enough to remove the cap and then refill Radiator.
I'm gonna check the door blend issue on my EX, but the heater hoses in my situation are still not very warm. So I gotta dig more. Bad weather has delayed my radiator shipment, so until I get it, I won't drain and dig. I'll post when I get somewhere.
i have a 94 explorer and my heat nor my air will work at start up.
after the vehicle has been running for about 5 or 10 minutes then the heat will work but only on high...
any suggestions?
Wow, wacky EX you have. could there be a short in the heater controls, or perhaps in the A/C compressor?
Update on my heat issues:
I took care of all my problems, except the wandering temp gauge issue. I found a ton of sediment and sludge in my heater core while I flushed it very thoroughly. I also cleaned out the heater core box and blower fan area of leaves and crap. Fan blows nice and strong now. Both coolant senders/sensors, the rad cap and the thermostat were replaced. My old cap was a 13# unit, the replacement I purchased is a 16# unit. I wonder how much of an effect it has made.
Before all this my temp reading was just inside the normal range, topping out just before N and the needle then would wander back and forth between the N the tick noting "normal" range. The heater hoses were not very warm and I had luke warm heat at best.
Afterwards, I go all the way to R/M and the needle wanders to A/L. I have lots of heat now, the heater hoses are nice and warm and she comes up to temp much sooner than before. I wonder if fuel economy will return since she used to get 2-4 mpg better range before this started happening.
I may have a bad head gasket, that would explain the wandering temp. I have to check out some things. I do not have coolant in my oil, well, no foaming anyway and there appears to be no residue that I can find. My coolant is all new, so I am not sure how long until I can check it to see if there are signs of combustion gases in it. Never doen that before. I have a gasket kit coming and am looking at 95tm heads for later on next summer.
Hope this helps some of you guys with heating/cooling issues.
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