I'm having an issue with my A/C in the summer. It's fully charged, but isn't perfectly cold UNLESS i disconnect my heater core. Mice infested the vents while it was stored and I believe they removed all the insulation on the vents so they leak through. I DID try adjusting them to make them tighter, but it didn't help much.

Last year I removed the lines going to the core and put them back in the fall and all was fine in the summer. I was thinking about putting a shut off valve in the lines at the fire wall for the feed and the return. Any thoughts on this causing any harm? just having it closed off and not circulating?

 

I do not know what is causing the problem but you only need one shut off, on the return side.
When I drove truck we had to do this to control the heater because the dash controls did not work, open the valve all the way, tons of heat, part way...spring and fall..summer, closed.
5 years and 500,000 miles and it didn't hurt anything, it wont hurt your truck either.

 

Because of the bypass thermostat and plumbing layout of the D2 I would consider a valve that bypasses and still allows flow from engine back to water pump, I would be concerned that external thermostat might behave strangely with a closed off heater circuit. See plumbing flow diagram. Like Spike, have done the shut off on old Chevys as well, but this may be different. Of course you could plug it and watch your temps on the engine to be sure. Any problem should show up in first few days.

My basis for concern is that when main stat is closed, hot coolant has to circulate through the top holes in the thermostat to warm up stat to open. The flow thru heater core may be part of the engineering equation from what whatever Klingon devised this cooling layout. Would not want thermostat to take longer to open.....

BTW, if you think the D2 has plumbing, take a peek at a Freelander, the clamp champ, also attached.

 

By-passing the heater core during the hot season is a huge mistake, your engine will not be able to run as cool as it should while the heater core is out of the loop.
You need to have someone test and find the electrical issue under your dash and fix it.

 

He by-passed his heater last summer and had no issues, why cant he do it again this year?

I'm just playing the devils advocate here, his problem sounds like it is deep in the dash and is going to cost mega money to fix.

 

Neither you and I or he knows that to be a fact if he is basings his information just on the factory temp gauge which doesn't move from the neutral spot from 150 degrees up to around 225 plus before it will start to climb.
Manual says doesn't by-pass the heater core, that is good enough for me.

 

The manual also says not to by-pass the throttle body heater...

I'm not arguing, just asking questions.

 

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