Mazda Repair: 1990 Mazda A/C issue, blower motor resistor, mazda b2600i

Question
Sir,
I have a 1990 Mazda B2600i 2WD pickup. My A/C only works on fan setting 1.  On this setting the A/C compressors kicks on and off and the air is cold, but as soon as I switch to a higher fan speed the compressor turns off and the air becomes warm and almost wet feeling.  A mechanic shop said the a/c blower motor resistor needed replaced, but I don't understand because the fan works on all speeds just not the air.  Also do you know where the blower motor resistor is located, inside the cab or engine compartment?  They want to charge me $125 to install a $26 part, if this will even fix my problem.  I would really appreciate your insight.

Thank You

Answer
Hi Isaiah  thanks for asking
 If you turn on the fan and and the ac shuts off but the fan  still works on all speeds, then it does NOT need the resistor. there may be a problem with the control panel that controls the AC, I would take it to someone that will check it properly..
good luck
Chris P