Heater/AC issue

dugger · #1 05-16-2017, 06:55 PM

Hello all, got an issue thats got me scratching my head. Sons 2000 Mazda made by Ford B2500 truck heater started leaking a few years back and a mech. by pass the core for him. I got the truck back and recently started working to get back on the road. Rel placed the core, theromstat, diverter, poteintialometer and cut the duct work to find the blend door is working find. Vacuum lines are in fair shape but seem to be working. Filled and burped the radiator but still doesn't seem to be getting water to the heater core. But what really is confusing me is that it seems to be in AC mode all the time. I noticed the condensor seems to be going on and off while in heat. I even disconnected the condesnor and felt the temp drop from the duct. I did add some freon and stop leak to the AC system and it seems to be working fine. I thought about the water pump but no leaks or over heating. Got any ideals and TIA.

sheltonfilms · #2 05-16-2017, 07:53 PM

Pull the water pump and look at the impeller fins. Could be rotted away. Temp will show fine but you won't have enough ummmph to get the flow through the heater core.

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dugger · #3 05-20-2017, 04:41 PM

Thanks Shelton, thats my next item to check. It feels like the AC is on all the time so I ordered the HVAC control switch tonight. If that doesn't work the water pumps coming off. This has really got me scratching my head.

sheltonfilms · #4 05-20-2017, 10:27 PM

By the way the compressor turns on every setting except for panel and floor. It's on with AC,Max AC, panel/floor blend, floor/defrost, and defrost. If it's on during those selections then the panel is working right.

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Heat doesn't matter if ac compressor is on. If temp knob is all the way on the red you get heat.

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