Hi Guys

Before you bring the pitchforks out, I live in the middle east so highly doubt ill ever need the heater

Looking for some clues or ideas on why this is happening

Scenario #1: We did the heater valve delete on my friends 99 XK8


P side valley hose is completely blocked off from the water pump side. The D side valley hose was retained with a 45 degree elbow connecting to the coolant reservoir. All the octopus hoses and heater hoses were removed but still kept the heater valve in place.

Now here is the weird thing, once we disconnected the 2 sockets for the heater valve and aux pump, the car ran like absolute trash. No power and misfiring however once you switch off the car and reconnect the 2 sockets, runs perfectly normal

Scenario #2:
2000 XKR, bone stock, out of pure curiosity, I also disconnected the 2 sockets for the heater and aux pump(while still maintaining all the pipes). AC runs cold at lower speeds but at higher speeds, it isn't

Any plausible explanations?

Thanks

 

Common understanding is that the heater valve defaults open, i.e. disconnected, it will allow the water to flow through. Even if the weather is cold, with the help of the electrical pump and inside fans, the inside of the car gets uncomfortably hot (I tried!). IOW, in a "race" between heater and A/C, heat wins out.

As you know, the auxiliary electrical pump is just a spinning magnet. The impeller moving the water has no mechanical connection to the pump. At sufficient rpm, the engine water pump produces enough pressure to push some water through the heater core, even if the auxiliary pump is off.

The auxiliary pump is always on when the control unit is turned on, hot or cold. There is a fuse you can remove to check if there is any weird consequence.

The heater valve defaults open. The control module turns the valve open and closed over a period of time to control the flow of hot water to the heater core.

You can check the details in the electrical manual on jagrepair, and see if somehow a ground connection became necessary trough one of these connections. A long shot guess would be that somehow the control module would loose its ground, and crash its associated data bus (ISO or SCP?), thereby confusing the ECU. Plugging in a proper diagnostic tool might tell you what is happening.

Best of luck, keep us posted.