A/C after heater core change....

Hummer H1 and Military Humvee topics
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JustinOK
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Joined: Tue 04 Sep , 2007 3:39 pm
hummer_info: 1998 TD HMC4
Location: Oklahoma City, OK

Re: A/C after heater core change....

Post by JustinOK » Sun 09 Jun , 2013 11:06 pm

From the AM General Factory manual regarding the vacuum pump:

"Vacuum Pump Test
The pump can be checked with a standard vacuum gauge. Output
should be minimum of 20-21 inches vacuum."
1998 TD HMC4 w/ 91K miles

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fusioncruiser

Re: A/C after heater core change....

Post by fusioncruiser » Mon 10 Jun , 2013 6:43 am

JustinOK wrote:From the AM General Factory manual regarding the vacuum pump:

"Vacuum Pump Test
The pump can be checked with a standard vacuum gauge. Output
should be minimum of 20-21 inches vacuum."
Ya, I saw that too... Apparently, that is if you test directly off the pump just before it splits off to the various lines.

Mine tested ok if I rev'd but not while idling so I replaced the vac pump and the pulley. I have perfect vac now but still have same heat/ AC problem. Water valve is next test.

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chuck
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Re: A/C after heater core change....

Post by chuck » Mon 10 Jun , 2013 8:53 am

I went to my parts cross reference page to update the vacuum pump pulley part you found. Guess what? The part number was already there.
http://flashoffroad.com/features/PartsC ... sRef.shtml
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Adobe
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Re: A/C after heater core change....

Post by Adobe » Sun 16 Jun , 2013 9:25 am

I had to replace the vacuum pump on my 98 hummer also. I couldnt get the only pulley off, (I took a chance and wound up bending it). My Tubro and AC both wouldn't work due to the vacuum pump. So you may start hearing a windy up and down noise once you fix it.

But for a new pulley I bought this it was the cheapest I could find.

http://www.ssdieselsupply.com/product_1 ... ulley.html

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