A/C compressor, IAC ??? help with 3fe (1 Viewer)

[rghouse]

when idling in the heat with A/C on the truck begins to shutter after about 5-10 minutes, but not always. The idle goes up and down (from 600-900 aprox) as if the engine is starved of fuel or low on radiator fluid. I opened the hood up and the A/C compressor was making a low pop or click noise as it shuttered. This caused the temps to creep up, the A/C still blows icy, and a step on the throttle will remedy it for a little while. If the A/C is shut off, it stops.

FC is modified, A/C is R/134 upgrade, everything else stock. This truck has always started bad since I've owned it also. After it turns over it is somewhat quiet, stutters a little, then starts idling.

 

[rghouse]

bump

 

[inkpot]

bump

Have you got a better temp gauge than the OEM dash gauge?

 

[CJF]

Bad connection at/around the compresoor.

 

[rghouse]

only stock gauge

 

[rghouse]

the cooling system has already been troubleshooted, and completely gone through including top end redone.

 

[rghouse]

Bad connection at/around the compresoor.

Electrical connection? Shoot I didn’t know what you meant. Maybe there is a short or a relay problem. I’m going to have to send it to the shop I think

 

[Alleycats]

With the A/C 'on' the idle goes up and down as the compressor cycles on and off. (this is normal)

Not sure what the shudder means though.

 

[rghouse]

The idle fluctuations are not the normal cycling of the compressor. It is rapid, up and down.

I now know it is the result of the compressor going haywire, on/off, on/off and so on. Gotta be wiring/electrical/sensors/connectors malfunctioning...or possibly compressor taxed/failing when hot.

Again, this only happens intermittently when ambient temps are above about 96, at idle

 

[Tools R Us]

Slightly overcharged?

 

[rghouse]

Ok, onto the pressure thing (thanks tools r us). Sounds like (thanks google) high pressure could be the problem. I found a good article on my sysmptoms:

Compressor Rapidly Cycling On and Off in Car Air Conditioner - BsnTech Networks

Here is the closing paragraph:

"So next time that your air conditioner compressor rapidly turns on and off in your car, it may not be due to low freon levels – but because it is over-charged! Those cheap low-pressure testers that come with the charge kits only tell you part of the story. When I was charging mine, I was well within the acceptable range – but the high pressure (which is what I couldn’t see) was telling an absolute different story!"

I do not have a high pressure gauge so I may have to take it down to my shop, or just let some pressure out. I'm really curious what my readings are though, at different RPMs, and at different ambient temps.

 

[CJF]

I'm really curious what my readings are though, at different RPMs, and at different ambient temps.

Gauges are pretty cheap, and available from Harbor Freight, Amazon, etc...

 

[4 ADVNTR]

when idling in the heat with A/C on the truck begins to shutter after about 5-10 minutes, but not always. The idle goes up and down (from 600-900 aprox) as if the engine is starved of fuel or low on radiator fluid. I opened the hood up and the A/C compressor was making a low pop or click noise as it shuttered. This caused the temps to creep up, the A/C still blows icy, and a step on the throttle will remedy it for a little while. If the A/C is shut off, it stops.

FC is modified, A/C is R/134 upgrade, everything else stock. This truck has always started bad since I've owned it also. After it turns over it is somewhat quiet, stutters a little, then starts idling.

My 91 does this too, but the A/C stops blowing cold when it does. Usually about 5 minutes after sitting still and idling. Still running stock fan clutch and R12.

 

[rghouse]

^^^ I am sorry to hear that, hopefully we can get to the bottom of it. The A/C was not blowing as cold last week during the compressor issues, but I attributed it to the heat. It didn't get warm, but it was not icy.

I have been beleaguered with Cooling issues ever since purchase, the list is long, very long I thought I was out of the woods, but no . After I get the high pressure line checked I'll let you know what I find out. I have never messed with the refrigerant since purchase in March 2015.

The A/C gauge set at Harbor Freight is $60 (thanks CJF):
A/C R134A Manifold Gauge Set