Hi folks, I have a peculiar problem with my 97 Ford Ranger XLT. Last summer, (I live in Ohio) I noticed whenever I turned on my A/C, my truck would lurch forward and make a clicking sound. I think the clicking sound originated from the A/C fan going on and off. Whatever, no problem it was almost autumn so I lived with it and figured my A/C died.

After some research, I thought maybe I had a vacuum leak within the system. I never got that inspected. Instead, fast forward to Summer 2020, I decide to recharge the A/C. That fixes the lurching, clicking noises, and blows ice cold air. Perfect. Fast forward a couple weeks later and now the A/C only blows extremely hot air and when I increase my speed the air blows out hotter and stronger. When I slow down, the air weakens and is still hot, but not as hot. Even when my fan is off, its blowing hot air at full blast.

Is my blower motor bad? Could it be clogged? Or did the A/C finally die on my 23 year old beauty?

 

First lets leave the AC off the table for now

The TEMP **** on the panel controls a electric Blend Door in the cab, this door directs air flow from the fan either thru the heater core or around the heater core, or anywhere in between, so with AC OFF see if you can control the temp of the air coming out, if its always hot then Blend Door motor is bad, not an uncommon occurrence in 1995 and up Fords

Google: Ford ranger Blend door

To see your options, lots of them, lol

Fan speed
Fan has 2 wiring paths, Full Power, or low/medium
So fan can only have low/med, and no full, or just full and no low/med
No low/med is the most common issue, this means the "resistor block" has failed
It's in the engine bay on the Heater Box next to the fans motor

Google: 1997 Ford Ranger Blower Motor Resistor

Very easy to change this part to get low/med speeds working again

Now to AC
AC is either on or off, it has no speed, or a high or low, just on or off
If your Blend Door is stuck and directing all the air from the fan thru the heater core then no cold air, and heater core gets hotter when you REV the engine, because coolant circulating thru the heater core gets hotter, which is why you check blend door first


BUT, in MAX AC setting the coolant flow thru the heater core should be shut off by the Coolant By-pass valve in the engine bay, the By-Pass Valve will have 4 heater hoses, and a GREY Vacuum line attached to it
When you select MAX AC in the cab, Vacuum is sent to the engine bay's GREY Vacuum hose and closes By-Pass Valve to stop flow of hot coolant into the cabs heater core

Check if thats working, with engine idling, select MAX AC and then go to engine bay and see if the Grey line has vacuum, pull it off the by-pass valve to test, you should see the valves arm move if it had vacuum and if valve is working
Not uncommon for the by-pass valve to leak coolant, and many just remove the valve and use couplers to hook the hoses together, in that case heater core always has hot coolant flowing thru it