A couple of problem I could use suggestions on

[Tynee]

I have 2 problems (beyond the swiss cheese sheet metal).

#1) Everything Electrical works fine at higher RPM; at Idle, the turn signals flash VVVEEEERRRRYYYYYY slowly, the heater fan comes on and off (only when on hi, could be due to a worn out relay) and all the light inside and outside get a little dim. Is this most likely an alternator problem, or is there somewhere else I should check first?

#2) Summer: Truck runs hot, new thermostat and water pump, still runs hot. Winter, temp qauge right where it should be, only get hot air out of heater at higher RPM, not very hot at that. Just a radiator that needs to be flushed?

[bigvinnie]

check frame, engine, and body grounding for the electrical problem...

heater problem is kinda strange... does your blower motor speed up and slow down with the rpm...?? could also be a grounding problem.... otherwise, your heater core may be toast and need to be replaced...

[wlee]

Also check your regulator - if the points are corroded the unit may not be making contact until you get the RPM's up.

You get Hot air from the heater?? That's novel

[jmil1974]

my guesses:
voltage reg. or ground problem

heater core and/or blockage somewhere

[Jmac05]

Heater core/blockage very likely...
However, check your mixture % You may need to run more water. It helped me in my truck when it was 100 degrees outside.

[Tynee]

Well, I guess that solves one problem. I stopped at Auto Zone to have them check the alternator. Sure enough, I'm gettin' plenty o' volts, but only 21 amps. That Alt is rated for 60. I'll put it on tomorrow and hope for the best.

On the heater thing, I checked the hoses. Rad to heater cont. valve is hot, valve to core warm, return to rad. stone cold. Have you ever heard of a year old core plugging up, but not leaking? The cooling system has never seen anything but distilled water and antifreeze. I'll change the valve tomorrow and hope for the best on that too.

Thanks for the help.

[da-burb]

Do you have factory A/C? I only ask because that is the only valve that would be in-line on the heater hose. If you do then that is your problem. It could be stuck shut or maybe the vacuum hose is connected to the wrong port and it is closing when it should be open.

[Hooter]

Could you have an airlock in the heater core?

[Fred T]

I think da burb is onto something. Before replacing the valve, check a couple of things. Does the valve have vacuum to it with the engine running and the heater on? Check it with a vacuum gauge if you have one. It should have a strong reading. If the reading is low, check your lines to the control and back to the engine. Also check the valve. Try blowing into it to check for a diaphragm leak. Sucking can get you a mouth full of crap. You could also take the valve out of the hose and see if you get heat that way.

[Hooter]

Ah you can always spit the crap out.

[Longhorn Man]

Bypass the valve.

[Huck]

Tynee, know the alt is not putting out but still take the time to check for good grounds---block to firewall, cab to frame, etc. Even a perfect Alt will not give you the results you need with bad grounds. My bet on your heater is that valve. Had to replace mine on every A/C truck I've had due to leaking or just not working. that vacuum line is also critical----I also wind up replacing all the vacuum lines, heater hoses etc. to ward off the deamons!! With everything working perfect it still takes me 4-5 miles before I get heat in either of my trucks~~. Let us know what you find out. Huck

[GloryHound]

Huck

I've found the miles all depend on how fast I'm going!!! HeeHee!!!

Sorry you all, just had to throw that in.

Da Hound

[Tynee]

Okay, put the alt. on, seems to have cleared up the electrical issue. Heater blower still a bit suspicious on hi, but I think thats the relay.

Now just the heater thing. I changed the valve and life got worse, nothing but COLD air. Bypassed the valve & can't stay in the cab without breaking a sweat. I've got about 17psi vacuum at that valve, surely that should open in, right?
I think I'll go look this up. Maybe the valve is backward, but that shouldn't matter once its open, should it?

[Tynee]

How 'bout it, anyone know how many psi I need to open that valve?



ttt

[Gordo]

I believe the valve remains open when there is no vaccum or if it's disconnected. When vaccum is applied it closes the valve. I think anything over 5 inches of vaccum would operate the valve if it's in good condition. Also, is the thermostat working? If it is functioning correctly it helps force the coolant through the heater core during warm up.
To check your ground condition, use a digital volt meter, set it to the 20V DC scale, connect the black lead to the neg post of battery, turn ignition on, engine off, turn on lights, heater on high and with the red lead, touch it to the radiater support, frame, engine and cab. Readings should not eceed 0.10 Volts. If the readings are within the 0.10 V limit, your grounds are fine, if the readings are over that, you need to clean up or add ground straps from neg post of bat to the rad support, engine to frame and engine to cab.

[Tynee]

Ohhh, then I have been working on completely the wrong assumption. I must have misunderstood. I was under the impression that the valve opened when pressure was applied. So what do I need to look at to see why their is constant vacuum to the valve? Can someone clear up all of the functions of all three levers on the heat/air controls? I know I've got one that is broken, and is probably stuck at one extreme or the other(top lever). I believe the bottom lever directs the air between feet/defrost vents, corrrect?


Thanks ofr any and all help!!