2005 STR AC blowing hot air in "auto"
 

The AC started blowing hot air the other day. Took it to mechanic, he replaced a fuse and AC was working fine. Let car sit and idle for 30mins and continued to blow cold. When I left, adjust the temp from "LO" to around 68 and hit "Auto" and immediately started blowing hot air again. Turned around and went back. After his second "look/see", he thinks the Aux.coolant pump is going bad and pullling too many amps and blowing fuse. Recommends replacing aux.pump to fix problem. He put another fuse in and AC is blowing cold but he recommended leaving it on "LO" until he replaces pump on Thursday....Just looking for a second/third/fourth opinion from you guys...have always given me good advice in the past...so, what do you think?

Have you checked out the temperature evaporator sensors? It's a common problem apparently. My a/c blew hot air while on auto as well unless the temperature was set to LO. Then, once in a while, it worked perfectly fine and was ice cold.

I changed out the sensors and never had the problem again.

Check the second post in this thread:

https://www.jaguarforums.com/forum/s...-sensor-35014/

You might want to find a new mechanic?

If the AUX pump fails the symptom is little to no heat. You should spend some time searching on this forum. Look for DCCV. Your problem is about the most common S Type issue.

Also post what fuse was replaced. That will help see what is on the circuit. You might have a bad A/C clutch that is blowing the fuse.
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tbird...I believe the fuse was "F"(?) 32...I know the 32 is right, not sure about "F"...

Do you have the electrical guide for your car? It's free on this site.

With a fuse blowing I would work on that first before replacing anything. If possible get the electrical guide so you can see what else is on that circuit.
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Sounds like the blend actuator servo motor (or a combination of HVAC servo motors) are malfunctioning or seized in "auto" mode... Auto mode controls the blower fan and actuator motors to keep the interior temp to the desired setting - I agree on finding a new mechanic... Lo should override all the settings and blow re-circulated air through the dash vents.

Hooking up a scanner and performing a HVAC diagnostic test should point out any of the servo motors not working as they should....

Thanks for all the input and I'm keeping it under my hat for now...here's a follow up question relating to the same issue...after the aux. pump was replaced, should the coolant be drained, flushed and refilled as the normal procedure? Would replacing the aux. pump cause any coolant to be lost? Once I get some input, I'll give you the whole story as to what he did..My air conditioner is working fine...so far...but even if it goes out again, I won't be taking it back to him.

Bound to lose at least a little so would need to top up and probably expect a bit of bleeding to be needed.