Almost never any heat. My GF says when she's on the highway for more than an hour, *sometimes* it comes on.

Here's what I checked:

1) All fuses in engine compartment, trunk, rear seat.
2) Changed out aux pump relay with another known working relay.
3) Connector on back of climate control (replaced radio in the summer and thought I may have knocked it out).
4) Coolant level and temps.
5) Disconnected connector to aux pump and checked for voltage. NONE FOUND with car running, and demand for heat!!!

Question: Does this aux pump come on all the time? Only when coolant temp is at a certain point? Is there ANYTHING other than the climate control system and relay that tells this pump to come on?

Do I assume it's the climate control at this point? Does that mean replacing that entire unit in the middle of the console?

Lots of questions, sorry.

 

Welcome to the forum tunnelboyjag,

When you get a minute, please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see.

In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

I've looked at the 98 wiring diagrams. The only thing controlling the pump is the relay (make sure you're not looking at the intercooler pump relay), the fuse (#15, 10 amp) and the power source (which comes directly from the battery).


The heater pump relay is on the left side of the engine bay, it should be the farthest aft and most outboard relay in the T shaped collection of relays in the engine bay fuse box. The fuse should be in the same box.


Try jumping pins 3 and 5, the pump should run even if the car is off.


Another possible fault could be the source of power for the relay, which is fuse #3, 10 amp, same fuse box.


NOTE: This is based on 1998 drawings, but yours is probably identical.

 

Maybe the aux heat pump motor brushes are worn out and its is not working? Ours was burning out the fuses.

I had to replace our 2001 aux heat pump with a used one, also had to replace climate control module with a used one.

We also had to flush the heater matrix (unclog it) before we were able to get any heat from the heating system.

Jim Lombardi

 

I had the same problem. It drove me nuts. I tried everything including replacing the auxiliary pump. Finally took it to a mechanic. Note: I had been ignoring the low coolant level warning light because the engine temperature never rose and when I looked in the reservoir the coolant always seemed to be full. So I thought it was a false alarm. It wasn't. Turns out there was a leak in the system. It was fairly high up in the reservoir, but it let the coolant drop just low enough that the auxiliary pump was not picking up the coolant and sending it through the heater. After the leak was fixed, the heat came on and worked just fine. Just a thought.