The Climate control system is blowing #F32 fuse in engine compartment fuse box. When the climate control system is off, it does not blow the fuse. When I turn it on everything works perfectly, cooling and heating balanced according to the temperature set, like it used to. Then after two minutes the fuse blows and I only get hot air. I replaced the DCCV valve about three years ago and when it gets power, before the fuse blows it works fine. I've read that when the DCCV gets no power, you get full on hot air. Any one ever deal with anything like this? I imagine that something is shorting it out, but what? If I tried it in the dark, with the splash guard removed to see things better, would whatever is shorting out be visible? Any input would be appreciated.

 

The Electric Coolant Pump will blown that fuse if it is faulty. The DCCV gets power from the same fuse so either one can draw too much current.
I had a customer that had a melted connector to the Electric heater coolant pump so a new pump and harness connector was required for repair.

 

Wiring diagrams here, courtesy of Gus:

Link to 2003 Wiring Diagrams


This two minute interval: Is it only after a cold start? Or even if the engine is already warm? I'm wondering if that is part of the logic so heat isn't commanded until the heater core is warm. The idea is not to blow cold air.

Correct.

Not at all. You may be thinking of checking for broken down insulation on spark plug wires, from the old days.

Look at figure1.2 for the fuse panel. Fuse F32 powers three items:

1) DCCV (figure 6.1)
2) AC clutch (figure 3.4)
3) Aux coolant pump (figure 6.1)

One of those three circuits would be your culprit. I'd suggest ruling out the aux coolant pump first, because it is the easiest to do. At the front power distribution box, unplug relay R7 and go for a short test drive. With relay R7 removed, the aux coolant pump is disabled. The heater performance will be reduced at low RPM, so don't be alarmed. Keep an eye on the coolant temperature, because in an overheat situation, the aux pump is commanded to run for extra cooling, but that shouldn't be an issue during cooler weather. If the fuse now behaves itself, the pump is bad.

There's a slight chance the relay itself could be at fault, but that is easy enough to rule out by swapping with a known good relay, such as R11 for the fog lights.

Try that and let us know. As previously suggested, also check the aux coolant pump connector for signs of overheating, too.

The AC clutch is easy enough to rule out, too. On the control panel, press the AC button once to turn off the little light. This turns off power to the AC compressor clutch. Go for a test drive and see what happens.

For the DCCV, you'd have to disconnect the electrical connector. I'd do that last because access stinks.

I can't remember what physical size the fuses are. If the standard ATC fuse, one of these circuit testers is very slick for reading amperage:


https://www.harborfreight.com/30-amp...ter-67724.html

 

Thanks a lot for all the advice and information. I removed the R7 relay for the auxiliary coolant pump today and the heating and cooling work perfectly now. I drove around for almost a half hour to check it and no problem, much longer than two minutes like before. I'm glad the AC system is OK. I'm also glad that the DCCV didn't die in only three years too. Tomorrow I'll try switching relays. That would be nice if it just needs a relay.
If the problem is the pump or a wire going to the pump shorting out, is there an easy way to find out which?
Is the auxiliary pump really needed?
I live on the coast in a northern California town and don't sit idling on the freeway in 90+ degree F heat all day.
Does the pump have a design that lets coolant flow through it when turned off, or is the incoming line blocked off? If blocked it might cause a leak in a while.
I'll probably replace the pump if needed by the summer either way. I recently replaced the coolant expansion tank and everything is fine now as far as level, no air, and no leaks in the system. I don't want to mess with it when it's working for a while if I can.

 

Yep. Reinstall the relay and disconnect the connector from the pump. On the slim chance the circuit has a bare wire rubbing against ground, the fuse would still blow.

If you'd really like to confirm a bad pump before replacing it, there's one more thing you can do. Turn off the ignition. Remove the relay again. Socket #3 will have 12V from the battery, hot at all times. Fabricate a jumper and connect it between sockets #3 and #5. This will route 12V directly to the pump, via the same fuse F32. You should be able to hear the pump run. The other two items normally powered by this fuse (AC clutch and DCCV) will not be powered with the ignition off. If F32 blows again, the pump is drawing too much current.

As above, you can further isolate the fault by disconnecting the connector from the pump. Try the jumper test again. Fuse blows = wiring fault. Fuse remains intact = bad pump.

If you really want to get fancy, use that amp test doohickie I mentioned in a previous post. You can see exactly how much amperage the pump is drawing.

I'd say yes. The pump has two primary functions. First is to improve heater operation at low RPM. If this aspect is inop, it's just an inconvenience. The second function is to help protect the engine in an overheat situation. If all else goes to *%#@, hopefully the aux pump will keep the engine from turning into an expensive paperweight. I wouldn't skimp on that.