02 hvac issue

[tgf]

Back story. My heater has been on the down hill slide this winter, a/c was weak this last summer. The week before Christmas the defrost couldnt keep up with the weather so I took it in and had the coolant system flushed and filled. Heater worked better but still not what it used to be.

Two days ago I about froze coming back from Joplin. I let the engine come to operating temperature with the heater wide open this afternoon and checked both hoses going to the heater core. Neither one felt any warmer than the air around the block. I let it cool pulled into my shop and pulled the heater core and used a sump pump to see if it was stopped up. It didn't appear to be plugged up, so I reinstalled it and checked the blend door actuator.

Question 1 should the actuator spaz when you adjust the temperature?

I also noticed the ac compressor cycling repeatedly when I went to recheck the hoses after reassembly. I unplugged the compressor and the hoses began to retain heat.

Question 2 what would cause the ac compressor to cycle like this, and how do I track down what is wrong?

Sorry for the long post but I'm at a loss and could use some help. Thanks in advance.

 

[co04cobra]

Behind the glove box the blend door actuator sets on top the heater box.

2 or 3 tabs hold it in place. You have to lightly pry up while pushing the tabs together to get it to pop out.

Once you get it out, plug it back in and more your knob from hot to cold and see if its working.

Other thing to do before that is confirm what the ECTs are at your upper and lower rad hoses and going in and out of heater core.

If everything is good at both places the rheostat on the heater control itself occasionally goes bad.


On edit: The a/c will and needs to cycle on every setting but floor only.

 

[tgf]

Behind the glove box the blend door actuator sets on top the heater box.

2 or 3 tabs hold it in place. You have to lightly pry up while pushing the tabs together to get it to pop out.

Once you get it out, plug it back in and more your knob from hot to cold and see if its working.

Other thing to do before that is confirm what the ECTs are at your upper and lower rad hoses and going in and out of heater core.

If everything is good at both places the rheostat on the heater control itself occasionally goes bad.


On edit: The a/c will and needs to cycle on every setting but floor only.

I have the blend door actuator out, it doesn't move smooth at all, kind of like the second hand on a clock that has a low battery. It will go from lock to lock, but will back off and try again if that makes sense. I am going to try again in the morning and see if the hoses will warm up.

Should the ac compressor stay locked in or should it cycle? Why does it run when the truck is set to run heat?

 

[TyCorr]

Sounds like its getting bad. The bda.

 

[co04cobra]

It does sound like the bda motor is getting weak. I would replace the unit.

The a/c only needs to cycle, its used to dehumidify.

 

[tgf]

I'll have a new bda tomorrow. What is a typical cycle frequency?

 

[tgf]

Update, replaced the bda, used it for an hour feeding my cows. The guage read motor was at normal operating temperature but still was not pushing the heat it used to. I'm going to replace the thermostat, but I don't think that will help much. Now where do I look?

 

[co04cobra]

Gauge on the dash is really telling you nothing. Use a IR temp gun and confirm temps at upper and lower rad hoses and the temps in and out of the heater core.

 

[tgf]

I'd forgot it was an idiot gauge. I'll check that

 

[Zaairman]

You said the hoses going to/from the heater core are not getting hot right?

Don't the newer trucks (ok, trucks newer than mine) have a valve that shuts off the coolant flow to the heater core? Might want to check that.

 

[tgf]

I checked temps today, forgot to get lower radiator hose. Upper hose read 75*, left heater core hose read 145*, right read 120*. Ambient temp never got over 5* today fwiw. Replaced thermostat and that helped a little bit, but not enough towarm up the cab. I'll have a temp guage tomorrow to check the lower radiator hose.

I didn't see a shut off Zach, but if there is one I've never touched it. The heater used to sweat you out in the winter

 

[co04cobra]

Is that full operating temp? Have ever replaced the water pump? Sounds like you have a pressure flow problem.

Your truck looks like a lariat. If it has the valve it's the first year for F series. It would be a round black valve teed into one of the heater core lines near the heater box. A grey vacuum line goes on the end of it. The vacuum line sometimes comes off, but shouldn't cause the drastic change you are describing.

 

[tgf]

The whole front of the motor was rebuilt January/February 2010 (damn black ice). Ive put about 50,000 give or take on since then.

With it being sub zero with windchill all day, would that affect the upper radiator hose temp?

 

[tgf]

I cleaned the accumulator and blower fan the best I could with what I have, I'll have to tear it down when it warms up a little bit to clean it better. Covered the radiator with a piece of cardboard with 2 6"x6" squares cut into it.

I'm still stumped. Thermostat houseing is reading 175, both radiator hoses read 145*, heater hoses read 165*. The heat is luke warm at best. Am I missing something?

 

[Zaairman]

Have you checked the blend door? I know they like to crack on F-150s and Rangers

 

[eng53ine]

Would the freon have any effect if it was low? I think I remember someone telling me once when my defroster in my 98 ranger wasn't working to check the freon. It also had a drain or vent tube that ran under the passenger side floor mat that was prone to plugging.


02 ccsb, lariat, 7.3 auto, 4x4, 4" duals, 6637,zoodad

 

[co04cobra]

Your temps aren't off that much. A little low but not bad.


You might try switching to a 203* T-stat.

 

[Vader's Fury]

Have you tested the actual heater core to see how hot it gets?


I think you have a flow problem, be it air flow or fluid flow. I think you should also check your blend door and make sure it is closing completely and sealing off the air bypass.

Also make sure it is not cracked/broken.

 

[tgf]

I got mad and pulled the heater core back out to step by step check my system out. the new actuator did not fully close or open the blend door and the foam on it was falling off. I repaired the foam with black tycoon (all I had) and cleaned and Re installed the old blend door. the rehostat (sp?) is messed you because full open or full closed on the dash causes a spastic action of the blend door. if the dial on the dash is slightly shy of full heat/cold it functions correctly. I had a new heater core here so I went ahead and swapped it out (cheap insurance). after fighting the thermostat housing last night and this Morning I now have heat.

this spring I am going to pull the accumulator to clean it better and check the resistance on the blower because I don't think It's pushing the air it should.