primerff

Its a manual heating & air conditioning system. When the heater is operating it tends to put out hot and cold air. The fan controller can change from low to high speeds but when the temperature controller is max out it blows hot then cold air intermittently. So can anyone tell more where to start troubleshooting this problem or have a resolution. If needed maybe some tuturiol info would help, THANKS!

RickMN

Be happy to help. In the heater box you've got an electronic "blend" door that opens and closes off air from the heater core or A/C. There are also two vacuum operated motors that open and close doors. One vacuum door direct air to either the floor/vent/defroster. The other vacuum motor opens and closes the door to outside air--that's what give you recirculation (closed) or fresh air (open).

If the temp changes based on whether you're accelerating or idling, then you should suspect a bad vacuum motor or leaking vacuum line. Otherwise, check out the wiring and condition of the electric motor at the blend door.

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steeler82

2000 Expedition having wierd heat problems. Front and rear heat blows warm for a while at idle, then begins blowing cold while driving around. But most of the time the front and rear blow cold, even at idle. Replaced thermostat, top off radiator with new antifreeze, heater hoses are warm – not hot, but still no heat. I have seen some postings about blend door but have not checked that yet. Any ideas?

jwko

The heater hoses should be hot. One a little hotter than the other with the heat on hot/high. Heater core could be plugged.

steeler82

Thanks for reply. I checked them closer up by the heater core and the one on the right is real hot, cannot keep hand on it and one on left is really warm, still able to keep hand on it. Since it's the less expensive option, I think I'm going to buy a thermostat from Ford, replace radiator hoses and flush out coolant system. I really don't think this is the problem, but it is the less expensive and money is very tight right now. Just got 5% permanent pay cut for us salary employees...better than layoffs. Thanks!

steeler82

Thanks to replies and previous posts, I now have heat, front and back...oh yes!!! As stated in my previous post, I bought a Ford Thermostat with O-Ring (pricey...$26 with tax), new upper hose (Advance Auto $17), new lower hose (Autozone $31), 2 gallons of Prestone Antifreeze 50/50 Extended Life (Autozone...buy one get one free mail-in rebate...already had 3/4 of a gallon at home), Radiator Super Flush, Zerex Water Pump lubricant (Advance $2 on clearance), Prestone Flush Kit, Extra Tee 5/8" on shelf next to the kit.

My main goal was to flush the heater core, but couldn't get to the heater hose clamps where they attach to the heater core. So, I ended up cutting (splicing) the heater hose on the outlet left side (inlet side, on right, goes to front of block). And I also cut the one of the right just before it plugs into the block. So now I had short open hoses going into the heater core. I put a female garden hose end (for mending bad ends on a garden hose) on both of them with clamps, which would easily allow me to hook up a garden hose to either end. First I flush from the outlet (left side) with water, and then with air. Quite a bit of trash and filty water came out. At first with water...ran til clear (5 min), then even more trash and dirty water came out when using the air (max 80 psi as advised from another post). When I used air, I put the outlet hose in an emply milk one gallon container so I could easily see just how dirty it was. Had to empty it several time, before it was finally clear. Then I used water one more time. Then I did the same from the other direction with water and air, so I felt good about the core being fairly clean.

I put a 5/8" Tee from the flush kit and the extra one on both of the splices (was tricky on the left side since limited space close to firewall). I flushed it following a Youtube.com post (YouTube - Flushing Your Car's Coolant System) flushing coolant system...very helpful. Problems I encountered were trying to catch fluid coming from drain plug and leaky connector from flush kit going into inlet Tee...had to keep a plastic container under it to keep from dripping onto my coil packs (which will end up failing once they get real wet). And my 00 EB Expy does not have a cap on the radiator...it's on coolant resovoir next to radiator. It was a problem since the tube from the flush kit was too small to fit. After trying to come up with a rigged up fit for 30 min, I gave up and ended up using good ole duct tape, wrapped around mutliple time til got a good fit and had to hold it in place...was a little bit of a pain.

Changed out top hose and thermostat with O-ring. Thermostat goes first and o-ring fits on top of it. I was unable to remove the lower radiator hose since I could not figure out how to remove the clamp holding it on the radiator. It had instructions on the band stating something along the lines of...Bend back tab and rotate hose to pull apart. I tried, just couldn't make it work. If anyone knows how to remove, please let me know.

I put in coolant and finally got nice HOT heat front and back...yeah!!! I regret not being able to replace the lower hose, even though original still looks and feels great. Also, I kind of wish of I went back with Dex Cool since that's what the original system was used to using. Thanks again for replies.