A/C warm at idle cold on acceleration

[GrumpierGrunt]

1999 Ford Ranger 3.0 Flex Fuel Automatic. 2WD Standard Cab 6 foot bed. 120,000 miles.

Last summer my A/C stopped working and I detected a strange smell coming from the vents. I replaced the evaporator and accumulater after discovering a leak (and plenty of UV dye) in the Evap housing.

I took the system to a shop to evacuate and charge the system up. They told me that the system was holding pressure but that the system was not blowing cold. At the time, I noticed condensation coming from the AC lines on the driver side of the vehicle. I proceeded to take the truck on a interstate roadtrip and found that it was blowing cold when I was cruising on the highway. Since then, I’ve noticed that the system will blow cold at idle on cool morning but blow cool air at idle on warmer mornings. When I drive at a high rate of speed, the AC will blow colder than the temp at idle.

After searching around, I found that the fan clutch might be the culprit. I replaced the fan clutch the other day and the issue persists. The fan clutch was definitely on its way out as the truck is a lot quieter at idle and acceleration.

I’m now not sure where to go, charging up my parts cannon since the truck is on its original compressor. Any help? Bad relay? Bad compressor? Can I try adding more Freon?

 

[Uncle Gump]

You sure the condenser isn't partially plugged up with bugs or has bent smashed fins?

Kinda sound like an airflow issue to me.

Edit... Have you had a set of gauges on the system to see what the pressures are doing?

 

[GrumpierGrunt]

@Uncle Gump
The condenser is probably about three years old, I will have to inspect it for any damage but I doubt it. While I was doing the fan clutch, I did notice a slight break at the very top of the condenser, not in the fins but in the very edge at the top of the condenser. No liquid or anything coming from it

I’m thinking of just laying down the $45 for the set of gauges from HF. I’ll probably pick them up this weekend.

 

[GrumpierGrunt]

When I did the evap work last year, I forgot to put in the expansion valve/orfice tube. Could that cause the symptoms? @Uncle Gump

 

[Uncle Gump]

I certainly doesn't help it... but not much goes wrong there except the filter gets plugged.

Your best bet is the check the condenser for blockage.... and put a set of gauges on it to see what it's doing.

 

[ericbphoto]

When I did the evap work last year, I forgot to put in the expansion valve/orfice tube. Could that cause the symptoms? @Uncle Gump

Yes, yes,yes!!!!!!!!!!

the orifice forces a change in pressure of the refrigerant from a high pressure liquid to a low pressure liquid. This is necessary for the refrigerant cycle to work and do it’s job. It can not function properly without that.

 

[Uncle Gump]

Yes, yes,yes!!!!!!!!!!

the orifice forces a change in state of the refrigerant from a high pressure liquid to a low pressure gas. This is necessary for the refrigerant cycle to work and do it’s job. It can not function properly without that.



View attachment 60706

Not quite true... even the graphic states that the expansion valve/orifice tube doesn't changes the state of the refrigerant... only the pressure/temp of it.

The refrigerant will actually change state from liquid to a gas inside of the evaporator. Fun fact... it will change states but remain the same temperature.

If the system is low it could change states at the valve but you would see a frost build up on the line at the orifice.

 

[Shran]

If I am reading this correctly, there is no orifice tube installed at the moment?

 

[Uncle Gump]

I think it's there... he just didn't put a new one in.

But I could be wrong.

 

[Uncle Gump]

I just re-read it...

maybe he didn't put the orifice in at all.

If that is the case... that is certainly the problem.

 

[ericbphoto]

He states that he forgot to put it in.

I was wrong with my “change of states” statement. But that pressure change is a vital part if the cycle. Without a metering device (orifice tube or metering valve) it will not happen and the system will not work.

i went back and edited my earlier post. I’m at work and got interrupted before I could double check my work against the diagram earlier.

 

[Uncle Gump]

Absolutely correct.

I read his statement completely wrong. Like he didn't replace the orifice.

 

[Shran]

Took me a couple reads through to get it all too

I would evacuate the system, put the orifice tube where it's supposed to be, vacuum and recharge it and see how it works. I bet that is what's going on.

 

[Jazzer]

There’s also the possibility that the compressor is wearing out, outlined in this article:

AC Manifold Gauge Readings | Troubleshoot Bad Compressor

How to troubleshoot with an AC manifold gauge set? The manifold gauge set will read a high low side and low high side if there is a problem with the automotive AC compressor. This is with the A C compressor clutch engaged.

www.freeasestudyguides.com

-Jazzer

 

[Uncle Gump]

There’s also the possibility that the compressor is wearing out, outlined in this article:

AC Manifold Gauge Readings | Troubleshoot Bad Compressor

How to troubleshoot with an AC manifold gauge set? The manifold gauge set will read a high low side and low high side if there is a problem with the automotive AC compressor. This is with the A C compressor clutch engaged.

www.freeasestudyguides.com

-Jazzer

Probably best to know if there is even an orifice tube in the system first. Without it there will never be any A/C.