Alright guys so I may just be having an old truck problem or there could actually be something I might be able to fix. Anyway as the title says my truck heater wont blow hot air until my truck is being driven, so on these cold as f**k winter days up here in washington when I let my truck warm up in the morning no matter how long she warms up for until I drive her she wont give me any sort of hot air. With that being said, if I let her warm up for a while she pushes hot air sooner than if I just "start her and go". Anyway, Ive read up on a few things, from what I see it could be a thermostat, bad fluid, clogged heater core, and maybe a few other things. I want to know if you guys have had any experience with this and maybe tell me where I should start, I was thinking probably with a thermostat replacement and coolant flush.

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1991 XLT 2x4 Ext. Cab. 3.0
Throttle Cable Mod, Off road lights installed in grill, plasti-dipped grill and headlight bezels, Angry Eyes Headlights, night shaded turn indicators, ford escort GT bucket seat swap, ford explorer shorty center console, roll-on bedliner.

The thermostat might be stuck open.

id start with a thermostat replacement, rad cap replacement and a full flush of the cooling system

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do you have any overheating problems in traffic or at engine idle?

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2021 F150 5.0 Screw

Past:18 F150 2.7, 16 F150 5.0, 14 F150 5.0, 07 F150 5.4, 03 Ranger 4.0

Master Certified Ford Parts / Warranty Admin

No I've never really had a problem with over heating

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1991 XLT 2x4 Ext. Cab. 3.0
Throttle Cable Mod, Off road lights installed in grill, plasti-dipped grill and headlight bezels, Angry Eyes Headlights, night shaded turn indicators, ford escort GT bucket seat swap, ford explorer shorty center console, roll-on bedliner.

ok than that should rule out the water pump

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2021 F150 5.0 Screw

Past:18 F150 2.7, 16 F150 5.0, 14 F150 5.0, 07 F150 5.4, 03 Ranger 4.0

Master Certified Ford Parts / Warranty Admin

I guess I should've mentioned that I replaced that just over a year ago

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1991 XLT 2x4 Ext. Cab. 3.0
Throttle Cable Mod, Off road lights installed in grill, plasti-dipped grill and headlight bezels, Angry Eyes Headlights, night shaded turn indicators, ford escort GT bucket seat swap, ford explorer shorty center console, roll-on bedliner.

The water pump could still be weak, and not circulating the coolant until the rpm's come up, will it blow heat while sitting and running the engine up to around 2500 rpm"s

First check the thermostat, but also remember that your fan clutch can take a bit to disengage high-speed until the engine is revved and driven just a bit. You can hear this if you start the truck and drive off, the fan clutch will release 30 seconds or so later. It could be since it's not driven immediately, the clutch is having trouble letting go at engine idle speeds, and is keeping the coolant colder than usual.

It also helps to not turn on the heater until the truck is warmed up; the heater core acts like a mini-radiator and the blower like a mini-cooling fan, extending warm-up times.

Might have the same problem as me. My 98 XLT was doing the same thing and I took the thermostat out and it was in there backwards......some ******* didn't know how to put It in there right I guess. The pressure from the water pump just caused it to always be open so my truck never truly warmed up.

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1998 XLT
2wd
Single cab
Hard flat bed cover
New pioneer head unit and speakers

Could just be low on water/anti-freeze. If short trips and cold outside temps, it won't overheat. Check coolant level first. Then next guess thermostat, them water pump. In order of ease of fix and cost.

are you sawing it won't blow any air until you put the truck in drive? Or the air won't heat up until you drive it?

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95 Ranger XLT 4x2 2.3 I4 5 speed 206,000 *dead*
96 Ranger XLT 4x4 4.0 V6 5 speed 173,000 *alive*
D35 front, 8.8 rear, 3.73 gears, limited slip rear diff

The air won't heat up until I drive

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1991 XLT 2x4 Ext. Cab. 3.0
Throttle Cable Mod, Off road lights installed in grill, plasti-dipped grill and headlight bezels, Angry Eyes Headlights, night shaded turn indicators, ford escort GT bucket seat swap, ford explorer shorty center console, roll-on bedliner.

thermostat or your not letting it warm up enough

The heater isn't going to work right away or after 5 minutes of running the coolant needs to heat up first

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95 Ranger XLT 4x2 2.3 I4 5 speed 206,000 *dead*
96 Ranger XLT 4x4 4.0 V6 5 speed 173,000 *alive*
D35 front, 8.8 rear, 3.73 gears, limited slip rear diff

My 94 Mazda B3000 was having the same issue. I just pulled the water pump off. It was the original water pump. The impeller resembled a saw blade. See the attached photos.

ForumRunner_20150112_004028.jpg

The old one.

ForumRunner_20150112_004042.jpg

The new one.

This was my problem.

Very cool. Thanks for posting those, Chris !