I only have issues with my A/C for some reason.

bought the truck from my father the a/c worked for the most part but the last few years he owned it the AC got weaker/warmer.

I had it charged with freon once and it was good for short time till it blew warm again after few months. After looking around found a small stone or something made a hole in my AC condenser (right on the tube). replaced AC condenser and dryer/accumulator and had it evac/recharged. Blows ICE cold now, but now i notice that around town it will blow ice cold all day long but if i go on the highway or interstate after 15-20 minutes it will start to blow warmer and warmer until its outside air temp. If i shut it off for 10 minutes then turn it back on it will blow ice cold again.

Again and again and again...

When it does this all the AC (compressor and such is still working), the blower motor (squirrel cage) still blows. the air temp coming out is just warm and kinda slows down a little.

A have read about and watched the heatertreater blend door fix and it seems to be what i am suffering from. any one else fix their AC issues with the heatertreater.

only other thing it could be is vacuum, everything thing like vacuum lines looks good and that would only cause an issue with air outlet location issues like "air only blows out defrost vent all the time"

$120 for the heatertreater door which i will do soon... and post back my results

thanks for reading and your advice/thoughts.

rickster

 

The blend door issue will be a constant and will not change with speed or a restart. MAX AC will bypass the door all together.

MAX AC does require a lot of vacuum to hold doors in postions but the air temp should not get close to ambient unless it say 95 outside, as the system has a hard time with super hot air on the intake.

 

For me it happens on both AC and max AC, the only difference between those two is the vacuum controlled outside fresh air (AC) and the recirculation (MAX AC) door. The vent outlet selector is also vacuum controlled and that works fine for me.

The blend door blends air between the heater core and the AC evaporator, but i read somewhere that in MAX AC the heater core has no coolant flowing through it, so i am thinking my blend door shifts toward the empty heater core and away from the AC evaporator causing my AC loss and outside feeling air.

On heater treater's website they say "blend door can shift/change during hard turns or bumps" and the door actuator/motor losses track of where it is, because the center plastic shaft of the plastic door is broken.

 

sounds like your evaporator is freezing up. This can happen if the compressor does not cycle. Check your pressure switche connectors to be sure they weren't bypassed during charging, and then not reconnected to the switches.

 

Not vaccum related. Evap seems to b culprit imo too

 

hmm, yes i could see that. i have seen the receiver dryer ice up when the AC is one under the hood.

How can i verify the evaporator is freezing?

going out to check the high and low pressure switches right now.

 

what sounds like is happening is the evap is freezing up and thats y it starts blowing cold and then it gets warmer cuz the evap is frozen and so no air is getting through then the it starts getting warmer then eventually the evap thaws and gets cold again.

 

the symptoms point to a frosted/frozen evaporator, I doubt you could get any easy access to verify

BUT, if the compressor isn't cycling, you have a problem, which will result in the blocked airflow.

It only happens on the highway, because you have maximum refrigerant flow, and maximum heat transfer from the condenser.

In town, it is nearly ice cold, but hasn't the capacity to freeze the moisture out of the air and block the evap core.

 

Makes very good sense. Yes i think when my AC is on the compressor stays on the whole time, i do not think i have seen my comp. clutch disengage on its own due to high pressure.

where and which pressure switch is the low (cycle) and high (cut-off) ?

 

my AllData shows both the A/C cycling switch and the low side charge port being in the line between the accumulator/drier and the inlet to the compressor.

Techs often will put a paper clip across the terminals in the harness that connects to the cycling switch so the compressor will run while they are charging.

Forgetting to remove this and putting the terminal back on the switch will result in just what you've got going on.

 

Check your low side pressure with the ac on max, your are looking for about 30psi. The cycling switch will operate the compressor from 21 and cut it off around 42.

If you are seeing numbers over that then the switch is shot, if its under then you might need a charge. You can change the switch with out evacuating the system or at least my 99 ford manual says you can.

 

I have a low pressure only gauge and a EZ charge can.

My compressor is running all the time, it does not cycle off ever. right now

I think i checked that a few weeks ago, when i was comparing my AC pressures to my wifes car. I think the low pressure stayed right at 30-32 psi and did not move. Any reason for this, i can recheck to verify pressure. Clogged orifice tube filter thingy? I have never replaced that, but i have one (motorcraft) i didn't replace it before because i didn't know where it was located...

 

30 psi gets you about freezing discharge air temp, at least in the rangers.

The orifice tube is in the drier, it needs to be replaced if you had to replace a compressor. The office tube is a flow limiter to maintain the desired output of the system(evap size).

 

I thought the OT was in one the ac lines. I thought i read it was in that line with a connection joint (lower line) coming out of the evaporator.

My compressor is the original

I replaced the condensor and the receiver/dryer with new ones and had a full evac, vacuum and recharge done about 3-4 months ago.