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Heater Problems (1998 3.0L)


Paraaronoid

New Member
Joined
Sep 30, 2008
Messages
1
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Vehicle Year
1998
Make / Model
Ford
Transmission
Manual
1998 - 3.0L 5spd Manual Reg. Cab; 190,000 km

I am baffled by this one, but probably don't have enough knowledge to sort this one through. I have very little experience, so it probably doesn't take much :)

Yesterday on the drive home from work I could not get warm/hot air blowing into the cab. This was a very sudden thing for me as I had nice warm air on my drive into work. Here in Sask., Canada our temperatures right now are in the -30C range, so anything that deviates from the norm (at least heat-wise) is easy to spot.

I have been doing some observing between idling in my garage and highway driving (anytime I took the temp, I put a thermometer directly in the air being blown through the vents):
1. Engine temperature according to the gauge reads exactly where it should be (half way).
2. When idling in my garage warming it up, it will take an excessively long time for the cab to warm up, although if left for 25 minutes or so, the temperature of the air blowing will go from 6C (43F) to 17C (63F). The engine temp. gauge will appropriately move from cold to normal operating temperature.
3. When the cab heat is blowing at 17C (63F), I took it out for a drive on the highway. Within a period of just minutes and only driving 6 km (4 miles), the temp of the air returned back to 6C (43F).
4. Once "warmed up", engine temp gauge is always where it should be.
5. Heater hoses going through firewall are HOT.
6. Upper radiator hose is HOT.
7. Black plastic shroud underneath dash passenger-side (close to the firewall) is also warm to the touch.

8. Coolant level was slightly low. I added about 1-2 cups to top up, but made no difference. I acknowledge that I haven't had it flushed in quite some time. Could this have accounted though for the "sudden" loss of heat?

9. I do only have Hot and Max A/C and have that for almost a couple of years. I just came across the "Blend Door Fix" and am pumped to try this out. I can't believe that this is the source of the problem though as I have been living with it for quite some time.

From my observations, the cab heat gets no warmer (but no colder) than 6C(43F) on the highway. In this kind of winter weather, it is obviously that I am getting SOME heat, just not enough of it. It seems that whatever heat I am able to obtain while idling is easily dissipated once on the highway.

Am I correct in saying that the engine coolant system (even though it hasn't been changed in a while) is working correctly? The heater hoses are hot, as is the top radiator hose. In other words, the heat seems to be correctly making it's way through the firewall and into the cab. This happened yesterday in -25C (-13F). I have managed just fine in some very cold weather just within the last week, -41C (-41F), so if it is weak coolant, would I not have had trouble during that cold snap?

Maybe a heater core blockage? Is there a way to easily test for this? I took off the hoses at the engine and blew through one and coolant came out the other. Would this imply that there is no blockage in the heater core? Or is that not an accurate test?

What about thermostat? It just doesn't seem that the engine itself though is over-heating in any-way shape or form. Is it possible that it could have fail-safe'd open, resulting in the colder (but still some residual heat) cab temperatures?

I do have the fan working (as evidence of blowing air) and I can correctly switch between blowing air at the feet vs. defrost vs. directly on, etc.

Any suggestions? Thanks a TON for your help! I'm looking through all of the threads now in this forum, hopefully I can find something there too.
 

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