No heat in the rear aux heater

Hummer H1 and Military Humvee topics
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94redklzese
Posts: 94
Joined: Tue 12 Feb , 2008 12:17 pm

No heat in the rear aux heater

Post by 94redklzese » Sun 03 Jun , 2012 6:24 pm

Sometimes I can't get any heat in the rear Does anyone know what could be wrong this usually happens when I mess around with the heat and switching it to ac then when I switch to heat I only get it out of the front and it will work for a min or so in the rear and than start blowing cold air only out of the rear heater
1994 ford probe klze
99 TD wagon
2006 gsxr 600

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h1sp
Posts: 2038
Joined: Fri 09 Feb , 2007 1:39 pm
Location: TEXAS

Re: No heat in the rear aux heater

Post by h1sp » Tue 05 Jun , 2012 1:20 pm

it sounds like its not the fan motor, so it could be many items from Blend door, actuator, vacuum line going to the water control valve and even the aux expansion valve.

I would start with the low fruit and check your small vacuum line leading to the water control valve (engine compartment passenger side) it sometimes falls off, but then that generally keeps it open and on HEAT.

let us know what you find
2000 HMC4
"Candy Apple RED"
Stock with Run Flats
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SilverRide98
Posts: 306
Joined: Tue 23 Jan , 2007 5:46 pm
Location: Cali

Re: No heat in the rear aux heater

Post by SilverRide98 » Thu 07 Jun , 2012 4:28 pm

It should be the control valve under the hood, it's easier if you remove the air cleaner canister. Then if the truck is warmed up have someone open the lever manually and see if hot water moves to the back. If not then it may have a bad flapper inside the control valve housing. When I did the change out of my A/C and heating units I ordred a NAPA part. If you look around for them one was $17 the other was $120. The only difference I saw was the cheaper one has the hose order switched and needed a little mod work, but for $100 it's worth it.
1998 H1Silver Wagon
122500 miles
Relocated FSD
WiFi Setup
Electric Fan w/Purple Ice
All Synthetic Fluids
Cepek and Toyo 37x13.5x17 Flat Black Powder Coat
Truck-Lite L.E.D. Headlights

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