I recently bought a 3.8L 2001 Mustang which had a blown motor.

I did a motor swap and on this new engine i am having some problems with the A/C . The compressor wont engage... I have checked all the relays, fuses and even changed the compressor!

Now when i was dropping the new motor in i broke the Coolant Temp Sensor. I haven't gotten around to changing that and i am wondering if that might cause problems with the A/C System?

Thanks for the help guys!

 

Does the system take a full charge? Does it hold a vacuum?

 

The A/C defaults off if the engine overheats, so if the temp sensor for the coolant is broken, then he a/c may not work.

 

if the temp sensor is unplugged (open) the pcm will read this as -40. if the temp sensor is shorted(wires touching)the pcm will read this as hight temp, this could cause the problem as stated by ryansquick6.

 

Yea right now the sensor is unpluged. I am going to replace it tonight and hopefuly it takes care of the problem.

 

Ok! Update!

I bought the Cylinder Head Coolant Temp. Sensor; and to my amazement on this motor no only is that blocked off on the back of the head, but the pigtail is not even there like on my previous 3.8L...

So here is the deal... The motor i swapped into this 2001 Mustang body has to be Pre 2000 because it does not the intake butterflys right?

So could me having a pre 2000 motor, harness and ECU be causing my A/C and Coolant Sensor Code?

 

It should go right behind the coolant neck in the lower intake. That was changed on 01+ also.

 

Yea i noticed it's there... and its even a different type of sensor; what are the chances that it is actually bad. I was replacing the one i thought would be in the rear of the head because since i thought i had broken it off.

 

It's a cheap sensor, as long as you're pulling it and having to rebleed the cooling system, might as well put in a new one. When you get you're new one, if you have to use a new connector or make an extension, you won;t have to worry about polarity, it should read fine either way you hook it up.

 

Would the harness from the firewall back ( into the car ) from a '99 and '00 be different from that of a '01+ ?