FIXED my POOR A/C Performance...
Lead Driver
Joined: Feb 2003
Posts: 8,140
Likes: 4
From: Oak Harbor, OH
The heater system is almost a separate system from the main cooling system. The heater lines are from the water pump back to the intake before the t-stat. It pumps the hot water from the bottom radiator hose, so no it won't hurt anything to put in a shutoff valve.
Sick 'n Tired
Joined: May 2006
Posts: 2,969
Likes: 47
From: League City, TX
Thanks! It looks like I'll be stopping by home depot tomorrow.
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New User
Joined: Jan 2005
Posts: 14
Likes: 1
Ran truck all day today.... it runs consistantly 10 degrees cooler with shutoff installed...
I am almost always at 40 degrees at all my vents now.. .. instead of 50-60 before valve..... it was about 111 today in Phoenix btw
I am almost always at 40 degrees at all my vents now.. .. instead of 50-60 before valve..... it was about 111 today in Phoenix btw
MMNC (SS)(Ret)
Joined: Mar 2004
Posts: 11,602
Likes: 148
From: SE Georgia
for those concerned about this hurting your truck
short term:
short term:
no, unless your hoses are brittle, this mod will have no affect on your truck. you should see a little improvement in cooling ability
long term: 1. cutting flow to the heater core will cause rusting and other corrosion inside the heater core since the water will be stagnant.
2. you will be subjecting that short length of hose to higher pressure than expected. the hoses are designed for free flow, not blocked flow. shouldn't be a problem, but I would expect hose failures if the hoses are brittle
otherwise, good job and nice mod. I prefer the auto valve myself, but the manual valve is extremely easy.
2. you will be subjecting that short length of hose to higher pressure than expected. the hoses are designed for free flow, not blocked flow. shouldn't be a problem, but I would expect hose failures if the hoses are brittle
Laughing Gas
Joined: Oct 2005
Posts: 1,058
Likes: 1
From: South Jersey
I think I will give this some more thought, and if I decide to perform this task, it may be a good idea to go w/ a vac-actuated set up. This way there will be minimal potential ill effects on the heater core and hoses. 
Fleet Mechanic
Joined: Jan 2007
Posts: 1,293
Likes: 18
Hey spoongooner; nice dam fix, buddy! The heater core doesn't have a valve from the factory because of the design of the HVAC system. However, you have demonstrated the shortcomings of this simpler and more reliable system. KUDOS! The difference in the cold air temperature is dramatic and will make all the difference on a hot day. For anyone concerned with corrosion in the heater core, use the Royal Purple coolant additive and give it plenty of time to circulate through the core before turning it off. I believe this additive is safe for all coolants including Dex Cool. If I did it, I might be tempted to put in a second valve and make a bypass line which would negate any pressure concerns. The plumbing now gets a little involved, but that doesn't stop a tinkerer! So, for cooling, bypass valve open and core valve closed. For heating, bypass valve closed and core valve open.
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