Stumble at idle after A/C Recharge (1 Viewer)

[ADVFJ80]

Afternoon all,
I've searched the forum and maybe am not sure what keywords to use

The truck: 1997 FJ80 with original motor. 251k overall, and 9k or so on the rebuild.

I live in Phoenix and my a/c wasn't blowing super cold, so I added some 134a yesterday. Brought the low side psi up to around 43-44, from 28. Aircon was blowing nice and cold until ...

The engine now stumbles like mad when the compressor kicks on. From around 800-ish, down to 600 or lower. Compressor kicks off after a short few seconds, and the idle returns.

This was a brief problem several months ago, but resolved itself as quickly as it appeared however, it didn't matter if the compressor was on and it wasn't this extreme an idle drop.

Video here:

I've not pulled the IAC to inspect/clean yet, and am wondering if I've somehow over pressurized the a/c system. If I drive with the a/c off, it idles/runs just fine.... But it's Phoenix.

Before I start completely chasing my tail, I thought I'd post up here for some other thoughts.

Thanks,
Randy

 

[flintknapper]

Normal for there to be a 'brief' change in engine rpm (at idle) when the compressor kicks on, but the IAC should increase the engine rpm to compensate for the drop fairly quickly.

In the video, unless you are manually turning the A/C on and off rapidly, then your compressor is 'short cycling'.

You will want to find the reason for that (typically the system is under or over charged).

 

[ADVFJ80]

Normal for there to be a 'brief' change in engine rpm (at idle) when the compressor kicks on, but the IAC should increase the engine rpm to compensate for the drop fairly quickly.

In the video, unless you are manually turning the A/C on and off rapidly, then your compressor is 'short cycling'.

You will want to find the reason for that (typically the system is under or over charged).

Not cycling the compressor on and off in th vid. Good to know about short cycling. Perhaps I need an a/c service at this point. Maybe I got the amount mixed up when I added the refrigerant.

Thanks for the reply!

 

[ADVFJ80]

Just to close this out. I did end up overfilling the refrigerant with the parts store kit. Quick aircon service at the mechanic, and I've got nice cold a/c.

Moral of the story .... Don't overfill!

Thanks again @flintknapper for the reply.

Randy

 

[flintknapper]

Moral of the story .... Don't overfill!
Thanks again @flintknapper for the reply.
Randy

De Nada.

Glad you got it sorted out. Too hot out there to be without A/C.

Take care, Flint.