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Originally Posted by kcheek
Hi,
The rear heater in my 89 Astro van is only blowing cold air. Any idea how I fix this problem?
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Welcome to the forum!
Insufficient rear heat could be caused by any one or more of several things. Faulty dash controller, Inoperative water valve, restricted heater supply hose, restricted heater return hose, restricted heater core, air trapped in the rear system, or even a weak water pump.
The first thing to check is the temperature of the hoses where they connect to the rear heater core. They should both be very warm to the touch with the engine running at operating temperature. A slight difference in temperature is normal. If the difference is very noticeable, there is a restriction somewhere either in the heater core, water valve, or return hose. If both hoses are cold, the water valve may be stuck closed, or not getting vacuum from the dash controller. While the engine is running, vacuum at the water valve should change when the controller is moved from hot to cold. An easy way to check for a restriction, is to remove both of the rear heater hoses where they connect to the cooling system under the hood. Connect a garden hose to one of them and check for sufficient flow out of the other hose. If the flow is not sufficient, track down the restriction and repair it. Water from the garden hose should flow with little restriction.
Bleeding trapped air from the system is tricky enough WITHOUT a rear heat unit. If trapped air in the rear unit is the problem, try this: with both hoses disconnected, (under the hood), hold the open ends of both hoses next to each other and fill one hose until fluid comes out of the other one. Once you are sure you have all of the air out, connect them back to the cooling system being careful not to lose coolant from either hose. Hope this helps.
11-04-2006, 01:56 PM
