Ford Ranger HVAC blows hot in AC - vacuum or electrical issue?

[nthach]

I’m trying to track down why a 1998 Ford Ranger I work on is blowing hot air despite being in AC mode. Checked the charge and it was a little low, added some virgin R-134a and UV dye. The pressures are fine now, 32/245 on the low/high sides. The electrical side of the system checks out - checked the relay with a Chinesium Power Probe clone - power and ground present at the relay, I can hear the relay click and the contacts are good. I also checked the AC clutch plug, also has power and I can see the HVAC control switching the ground on and off.

This leads me down two paths - vacuum leak at the dash connector for the HVAC damper doors or condemning the controls but I’ve been reading a bad blend door actuator or broken blend door might be at play. Am I going down the right path?

 

[Cruisin'n5thgear]

Bad blend door could be likely. 1999 Taurus that I had needed replacement of the motor a couple times. Not sure if that's relevant to the Ranger of a similar time period or how extensive the parts bin sharing was at the time.

 

[nthach]

Bad blend door could be likely. 1999 Taurus that I had needed replacement of the motor a couple times. Not sure if that's relevant to the Ranger of a similar time period or how extensive the parts bin sharing was at the time.

Well, if Dorman makes a replacement door and if the Ranger forum says so, that’s a good point. The problem now is the AC is intermittent, and Fords use a blend door to direct airflow towards the evaporator or heater cores, almost in a similar fashion as a Japanese car.

 

[brages]

1998 Ranger should have a heater control valve that will cut off flow to the heater core when the A/C is on max.

If your blend door is stuck in the middle, it may give cool air on MAX but hot air when you switch to regular A/C. My 1997 had this common problem. The Dorman door is not too hard to put in and has an improved design with a metal insert.

My 1997 also had a pressure switch go bad, but that doesn't match your symptoms. I don't think it's going to be a vacuum issue.

 

[Lubener]

Some time ago, my father had the exact same issue with his 97 Ranger. It was the blend door.

 

[Nukeman7]

Also take a look at the hard nylon vacuum line(s) in the engine bay. I had a gray vacuum line going to the vacuum accumulator canister abrade against a seam on the passenger side fender which created a pinhole that caused the A/C airflow to become intermittent. This was on a 2003 Ranger XLT, but I think the HVAC vacuum controls are identical.

 

[Fattylocks]

Probably the blend door and if it is you'll wish you had sold the truck two week ago.

 

[brages]

Probably the blend door and if it is you'll wish you had sold the truck two week ago.

It's not hard if you cut the box and then tape it back up. I used a mill bit in a Dremel.

My blend door came with the tape. Approximately one hour diy job.

 

[nthach]

It's not hard if you cut the box and then tape it back up. I used a mill bit in a Dremel.

My blend door came with the tape. Approximately one hour diy job.

I’m looking at the Dorman kit. As much as I know that brand is hated. I’m not pulling out a nearly 30 year old dash and risking breaking connectors or fittings.