A/C help/tech thread

[JB]

I really do not know much about A/C systems, but I know the basics. No tech in here, but maybe some can add their knowledge. Here is the problem that I am having on the 90 Bronco.

The A/C blows nice and chilled, and then it will get less cool, not hot, but just less chilled, then it will get cold again. Very intermitent all day. It really seems to have nothing to do with speed of the vehicle. The A/C clutch does not engage when I hit the throttle, so I think this is my issue. Refrigerant wise, I am good. We hooked it up to the machine and it was overcharged so we fixed that and got the correct amount of 134 in it.

I also replaced the A/C switch on the evaporator.

Is is common for the clutch itself to fail?

I appreciate the help. Thanks

[fbronco86]

I really do not know much about A/C systems, but I know the basics. No tech in here, but maybe some can add their knowledge. Here is the problem that I am having on the 90 Bronco.

The A/C blows nice and chilled, and then it will get less cool, not hot, but just less chilled, then it will get cold again. Very intermitent all day. It really seems to have nothing to do with speed of the vehicle. The A/C clutch does not engage when I hit the throttle, so I think this is my issue. Refrigerant wise, I am good. We hooked it up to the machine and it was overcharged so we fixed that and got the correct amount of 134 in it.

I also replaced the A/C switch on the evaporator.

Is is common for the clutch itself to fail?

I appreciate the help. Thanks

The A/C system will turn off when you hit the skinny pedal hard.

[JB]

The A/C clutch does not engage when I hit the throttle, so I think this is my issue.

i guess what i meant here is that it does not disengage

[fbronco86]

i guess what i meant here is that it does not disengage

Sounds like you have the wrong amount of freon in the system then.

You could check the clutch its just takes 12 volts to power it. Hook it up the battery and see if it hangs.

[mudtoy67]

How fast does the cool/not cool alternate? Do you have mechanical or electric fan? If mechanical have you ever put a fan clutch in? How did you check your charge? Did you drain and vaccum the system, or just suck some out in the machine until you thought you had the right pressures?

[JB]

How fast does the cool/not cool alternate? Do you have mechanical or electric fan? If mechanical have you ever put a fan clutch in? How did you check your charge? Did you drain and vaccum the system, or just suck some out in the machine until you thought you had the right pressures?

We drained it, and put a vaccuum on it then filled it to the correct amount(cant remember how much, but the specs were listed on the evaporator(orginal Ford)

The fan is mechanical. As for how fast it alternats, it is pretty random. Like it might be cooling fine from here to campus, then it will get less chilled. The ride home it might be chilled again or it my be warm. The system sweats pretty good, but the evaporator never freezes.

[fbronco86]

We drained it, and put a vaccuum on it then filled it to the correct amount(cant remember how much, but the specs were listed on the evaporator(orginal Ford)

The fan is mechanical. As for how fast it alternats, it is pretty random. Like it might be cooling fine from here to campus, then it will get less chilled. The ride home it might be chilled again or it my be warm. The system sweats pretty good, but the evaporator never freezes.

The specs are for r12 not 134a. I think normally it takes less 134a.

[JB]

The specs are for r12 not 134a. I think normally it takes less 134a.

yeah, i can not remember what the conversion factor is though. maybe 80% of what the r12 level is suppose to be? Anyhow, we knew that when we put it all back in.

[fbronco86]

yeah, i can not remember what the conversion factor is though. maybe 80% of what the r12 level is suppose to be? Anyhow, we knew that when we put it all back in.

oh ok cool.

my bronco never really worked great with 134a. It sucked driving around town but when it got the freeway it would cool nice.

[tigweld]

some older system are just not efficient enough to run 134a, I tried to convert my older vintage air on my 68' wouldn't work at all.

[fbronco86]

yeah, i can not remember what the conversion factor is though. maybe 80% of what the r12 level is suppose to be? Anyhow, we knew that when we put it all back in.

Was a 134a orfice installed?

[Graystroke]

just get a window unit and run some inverters or get an RV A/c system and put it on the roof.

[mudtoy67]

Here's a technique I learned from a seminar I went to when checking 134a levels in converted systems. The reason to go in to such detail is that if you go by the 80% rule and are undercharged, you may damage the compressor. This is because 134 systems rely on the refigerant to carry the oil through the system.

http://tamor.org/forums/showpost.php...06&postcount=5

Besides that I'm not sure what to tell you about why it would be alternating. Like the other guys said, 134 conversions often don't perform as well as r12.

Do you know if when you did the retrofit you put an automatic-adjusting orifice tube, or did you put a standard (non-adjusting) orifice tube? If you put an automatic adjusting one, that would explain the alternating temperatures, as the tube adjusts itself. You might need to swap to a standard tube.

[JB]

I did not convert it to 134a. It had been done a while back, so yes it does have 134a fittings. Ill try the tip in your link above. Thanks

[JB]

I think we figured it out today. When I tap on the clutch, it will engage. The clutch coil is probably weak. I took off the hub and removed one of the washers and it works great for now.