1996 Jaguar XJ6. heater won't work. replaced heater auxiliary pump and heater control valve. water hoses are heating up on one side but not heating that goes through the firewall. Any suggestions as to what to do next?

There could be a few possible causes for the rear heater not blowing hot air in your 2003 Chevrolet ASTRO van. Here are a few things you could check:

1. Make sure that the rear heater control valve is fully open. This valve is located near the heater core and controls the flow of coolant to the rear heater.
2. Check the coolant level in the radiator. If the coolant level is low, the heater may not be able to produce hot air.
3. Check for any leaks in the coolant system. If the system is leaking, it may not have enough coolant to produce hot air.
4. Check the thermostat. If the thermostat is stuck closed, it may not be allowing enough coolant to flow through the system to produce hot air.

If these steps do not help, it is possible that there is a problem with the heater core itself, or with other components of the heating system. It may be necessary to have a mechanic diagnose and repair the issue.

3 possibilties(1) Bad secondary water pump motor.Its located on left side inner fender by firewall under hood.The pump looking thing with 2 heater hoses and 1 cable connection (2) heater valve near secondary pump, 4 hoses 1 electrical connection.Power on to shut water off to heater. (3) blocked heater core.

MILES? CAN BE A PLUGGED HEATER CORE, HEATER CONTROL VALVE? ARE THE HEATER HOSES HOT GOING INTO THE FIREWALL??

All cars have what is called a heater matrix , this car has, it is inside the car behind the dash, the purpose is to provide heat in side the car, if the car is running at normal operating temp you thermostat is ok, the heater in the car is known as a heater matrix and will block up due to lack of use as water on passing throu when you have the heat on in side the car , hence the water leaves risidual that blocks it, if you keep a good level of antifreze/summer coolant in the systym it will prevent this, it is also the first palce to be affected when you lose water from the cooling systym, i will foward the detail how to clean it out, as removal is very labour intensive,

have you checked for hot water in the pipes ??

If you look by the firewall there are two hoses. They go into the heater core. When the engine is warmed up, and the heater on. Feel if both hose are equally warm. Be carefull you don't burn yourself. A valve lets the hot water circulate through the heater core therefore providing heat. Also feel if the heater core is warm under you dash on the passenger side. If it feels cold then water is not circulating. Locate the valve, which is usually vacuum operated. See if there is vacuum there when the heater is in the on position.

Check the auxillary water pump located on driverside of firewall between heater control valve and engine. That was my problem and it worked great after replacement.

do you have the old control valve , look how you took that valve off and install the new one the same way . rule off thumb is that the top of the valve will be the feed coming from the water pump and the other side will be the retrun good luck kdc744

There is an electric auxiliary water pump for the heater near the bulkhead. This is likely to be seized and may require replacement, quite a common fault!

due to the fact there is duel zone heating in these cars there is a heater control unit could a amplifier these tend to fail and you wont be able to get any heat a genuine unit is very expensive around $1500 but if you shop around you can get one for around $250 non genuine
then its just a matter of getting a jag tech to fit it

good luck