I have a question for RonD if he’s listening
now that it has turned colder I am using the heater a good bit I noticed the other day while idling in the Walmart parking lot that my heater has gotten just warm. I ripped the motor up to about 2000 for a minute or so and it got hot again. Does that mean my water pump is about worn out? I have already checked for Blockages and my heater core is clear and the blend door is working as it supposed to.
Larry

PS: and by the way which color wire on the heater control valve controls the compressor I am going to put a cut off switch on the compressor because I am sure there is some leakage in my heater box being 24 years old.

 

I am not RonD (my idol though) but it helps if you mention: Year,(not everyone good at math lol) Engine size, mileage etc. What did you actually do to check for blockages? Flushed the heater core? If so, you just may have an air bubble that hasn't worked out yet. Water pump could be weak..that depends on mileage and coolant condition. Neglected coolant can actually eat metal through electrolysis or pH level.
As far as the AC modification, the attached document to this post helped me.

 

That’s what I did first blew it out with air into very clean white bottle didn’t really see anything in the bottle. then I run water through it for a long period was getting a full tube flow.
The truck has 160,000 miles on it WaterPump appears to be OEM. I recently installed a dual core Radiator. Disconnected the heater hose to let all the air out when I filled it with new 50-50 when I got the truck about a year ago it had clean antifreeze in it and a fairly new single core Radiator. Next morning the radiator was full to the top and the overflow bottle was down about an inch so I assume that it worked the air out of it’s self. And as I recall the heater worked fine last year. I read somewhere that if the heater got cool at idle hot when you revved it up that that was a sure sign of a worn impeller.
Thanks for the link that’s just what I needed.
Larry

PS: I had a bout last fall with it overheating I was waiting in line to dump a load of trash and I noticed the gauge was climbing and just kept goin till it boiled. I’ve replaced several parts you know the usual thermostat hose flushed it out and fan clutch which was definitely weak. The truck had plenty of coolant in it and had never showed any signs of overheating prior. It was 95° that day. And has not overheated since I never did know why it overheated. Must have been the thermostat. The water pump is about the only part I haven’t replaced.

 

Things that cause low or no heat:
Low coolant level
Air blockage
Clogged heater core
Low circulation from corrosion or bad water pump, pinched/collapsed hoses, clogged radiator
Temperature control door in heater box malfunction
Thermostat stuck open, but it would eventually warm up if it weren't arctic out

If I missed anything, feel free to mention it.

 

Thanks for the reply and that list pretty well rules out everything except the water pump.
The heater core has been checked flow tested and blown out or visa versus, the hoses are good or new The blend door is working as it should I have an opening cut where I can actually see & feel it work. All other heater controls are working as they should. The radiator is less than a week old (2row) and it was 40° outside the thermostat is only a few weeks old and is going to be replaced soon with a hotter one. Since I put the two row radiator in it takes a long time to warm up if a cold day. The only thing that I can’t inspect is the water pump. So as soon as I catch a couple of warm days I’m going to replace that old water pump.
Thanks all, Larry

 

Idling in the parking lot at Wal-Mart ???
Is that from cold or is the truck fully warmed up ?
If you're running a cooler thermostat and you have installed a duel core rad, then an idling vehicle is not going to get very warm in cold or freezing weather.

Duel core rads are good at keeping the engine cool in the hottest summer days when pulling a trailer or hauling a big load, not so much to keep the truck warm in the winter.
Install the hotter thermostat and see if that doesn't fix your problem.
Don't let the the truck sit their and idle to get it to warm up, all you're doing is wearing your engine out and sludging it up.
Put a block heater in it, start it, let the oil circulate for a few seconds and drive it right away.
Adding a shroud over the grill can help too.

A worn impeller will cause over heating, even in the winter because of poor circulation.
Is it over heating ?

 

So are you saying that if it’s not overheating that the water pump is not bad period. Conversely if it’s not overheating then the water pump is good? actually the truck was warmed up. I had driven about 10 miles before I got to Walmart I put a new 192° thermostat in about three weeks ago but it has never gotten halfway up on the gauge only goes about not quite a forth of the way up. (185°) Like a dummy I did not put the new thermostat in a pan of water before I put it in the truck I am suspicious that it is not as marked. I have ordered a 195° thermostat a Motorad. I was told they were the best but you know how that goes.
The truck has never overheat since last fall as I mentioned above when it was 95° outside And I think the thermostat stuck. I never was sure what made it overheat. I’m going to put a switch on the compressor so I can turn it off and not put any cold air into the box. As I stated earlier the box is working perfectly however being 24 years old I’m sure there is some leakage around the doors. But correct me if I’m wrong even a new water pump is not going to circulate as much water idling as it would at two grand? So in 40° weather with a 24-year-old heater box and idling I may just have a normal situation? Oh and by the way even at highway speed‘s the heater doesn’t get super hot just very very warm. A guess would be the air is about 125°.

 

Yes, that's what I'm saying, at this point I think the water pump is fine.
Before going to all that work of replacing the water pump, install the hotter thermostat.

 

That’s what I will do it will be here tomorrow 195° Motorad.
Larry

 

When filling:
Fill the the rad just before it reaches the neck of the cap and start the truck cold with the cap off.
The level in the rad should drop noticeably.
Continue to slowly add coolant and "burb" the bottom rad hose while adding coolant _ the heater control should be set to the hottest position.
Watch the level at the rad cap and place the cap on just before it over flows.
Make sure and have at least 1/3 full in the over flow tank.

 

Did you ever order a thermostat to be one temperature and it come in another. The thermostat I ordered from Amazon was a 33479 Gates thermostat. When it came in it was stamp 192° on the bottom of it. I also got a motorad thermostat a while back that was ordered as a 195° When it came in the box said 195° but it was stamped 192° I don’t know maybe they don’t make a 195 thermostat. Or maybe that stamped temperature is not a temperature at all- maybe that means something else now I just don’t know?
Now I’m sitting here with a 33479 Gates thermostat that I don’t want to use and Amazon is sending another 33479 to replace it. LOL
Larry

 

I've had the best luck with Motorcraft and Stant thermostats. My records indicate I have a 197* Motorcraft in it and if I remember correctly, it said 195* on bottom of it. I don't think a couple degrees is going to make a significant difference and I'll admit I'm not an expert in thermostats. I have bought bad ones though.

 

My new motorad 195° thermostat arrived this morning I installed it drove to Walmart a little warmer today about 45° truck warmed up to normal almost halfway on the gauge and heat is very hot problem solved.

Faulty thermostat..

Larry