intermittent heat

[Wayne Sihler]

Did a thorough check of the vac line routeing just a few minits ago during an oil change. 96 XJ
Vac comes off intake manifold thru check valve>firewall around back of engine and under the area of the AC lines,Washer bottle and the hot water control valve.There is a T-fitting with a small line that has a check valve which turns and goes into the firewall at the same place the vac line comes out to the hot water valve.
Main line continues to vac blimp--
HTH
Wayne

 

[Blaine B.]

Blaine are you talking about the white line that goes through the firewall near the A/C lines?

Yes sir!

If you turn your HVAC controls to MAX A/C or OFF do you observe the pin of the heat valve being sucked up? AKA, the valve is closed....let us know.

 

[riverfever]

Yes sir!

If you turn your HVAC controls to MAX A/C or OFF do you observe the pin of the heat valve being sucked up? AKA, the valve is closed....let us know.

Didn't see that you replied back Blaine. I see 3 diaphrams behind the dash in the HVAC area. When I slide the control to OFF, one of them does get sucked or pushed up. It is the one that is vertically oriented with the diaphram at 6 o clock.

None of that may matter now:

I was bored so I went out in the garage and started looking at the vaccum lines. I grabbed the one that leads into the main canister and decided to clean it. I relocated the canister inside the engine bay months ago. Looks like that line was touching a radiator hose and it melted through. I cut out the bad section. I don't know if that fixed things or not but I'm hopeful b/c it was a big hole. We're still getting dumped on so I'll wait until tomorrow.

Thanks for all the help guys.

 

[Blaine B.]

I was talking about the heater valve, between the heater core and the heater hoses...

Start her up and let us know if you fixed it or not!

 

[riverfever]

Sorry man...I was looking my OTHER heat valve.

Yes...the one I was supposed to be looking at does indeed get sucked up when the heat is OFF.

 

[Blaine B.]

Doesn't sound like a vacuum problem (well the main line is intact, anyway)

If the main line was cevered and not giving any vacuum, it would keep the valve open regardless of position and the vents stuck on defrost regardless of position as well.

Try again driving around. If your canister line was severed, and accelerating when vacuum is the lowest, your vents might default to defrost if vacuum is lost....

See what happens now that you repaired that line! (When ya can, that is)

 

[riverfever]

I didn't pull my head out my arse and figure out what you wanted me to look at until AFTER I repaired the main vaccum line so the heater valve could have been doing something totally different 20 minutes ago. I'll let you know what happens when I drive it.

 

[Blaine B.]

At idle there should be enough vacuum where you wouldn't need the canister, however.....so like you said when accelerating less heat blows out because vacuum is being taken away and it is defaulting to defrost, since there was no canister (before, anyway) to store vacuum in with all of it leaking out the melted line.

Cross yer fingers

 

[riverfever]

Did a nice drive today and all seems fine. Thanks guys.

 

[Blaine B.]

Congrats, one less frozen driver on the roads:wave: