wierd a/c pressures and no cold air

[Maniak]

wierd a/c pressures and no cold air -- UPDATE WITH SOLUTION

I finally got a real set of gauges (my old set was just a low side gauge)...

Here is some info...

Outside temp close to 90F..
Static pressure 100psi on both high and low side
Running pressures (idle).. 70-75psi low side 200psi high side

This is a '92 Explorer with an r-134 conversion (about 1+ year old) with a Variable Oriface tube (VOR), new lines, compressor and condensor.. the evaporator was flushed.. All was fine after the conversion...

The a/c was running great back in January/February (I used it on the 80f+ days).. It blew cold.. on the freeway it would be 35F or so... a/c on high at idle with doors open was < 50F..

In all my reading so far, I've never seen a chart that showed normal High pressure (I "think" my 200 is normal) with a high low pressure.. I don't know where to look now..

Anyone have any insight on this?

thanks...

~Mark

 

[Glacier991]

generally this is indicative of a bad compressor - although I don't know whether the VOV could maybe be stuck (since these things are new and aftermarket, they are not usually a consideration when troubleshooting a FOV system from the factory and hence not mentioned in troubleshooting manuals).

I'd be inclined to rap the VOV bump in the line and see if maybe you can jar it loose IF it is in fact stuck.

 

[Maniak]

Thats what I was afraid of.. bad compressor.. I could just change the VOR, but from my reading it not common for them to fail.. and when they do.. they get plugged.. not stuck open (which is how mine would have to be to have high pressures on the low side)...

Guess I"ll get another compressor, VOR and might as well replace the receiver/dryer while I'm in there (since your supposed to when you open the system)..

Now I need a vacuum pump so I can do it all myself..

Anyone have any experience with the venturi style pumps? will they pull enough of a vacuum? (I'm 3500 ft, can be 2500 ft if I go into town with low humidity 10%ish )..

~Mark

 

[Glacier991]

They are barely adequate, and generally if you run em long enough as you should you will overheat the air compressor running them - most home air compressors are not rated 100% duty cycle.

PM me about a vacuum pump.

 

[Maniak]

issue fixed..

I decided to do a quick fix on the system and got lucky..

I pulled the hose off to check the VOV (orifice tube) and got a nice suprise.. I can't find the orifice tube. I know it was there a year or so ago when I converted the system but now I can' tfind it.. Which would explain why it looks like I"m not getting a pressure drop..

The only thing I can figure is that maybe I over charged the system (or the evaporator tube ridges are worn) and the orifice tube moved into the evaporator.

I checked and I have good flow through the evaporator so I just put in my new VOV, evacuated the system (I could only get 26" with the venturi style pump.. but I just needed some a/c for now.. I'm going to change the evaporator later and use a real a/c pump)..

I put in 20 oz of r-134 and now my low side pressure is 35psi, high side is about 210 (its was 100F in the shade). At idle, with a/c on max and fax on high I get about 55F air.. On the freeway I get 40F..

I'm thinking I may be slightly under charged..

Anyone Remember the amount of freon to put in? I "think" its 28 oz of r-12, but not sure about r-134 (I "think" it should be 24oz)..

 

[Glacier991]

It's 32 oz of R-12, so put in 65-75% of that for 134.

 

[Rhett]

I put in 20 oz of r-134 and now my low side pressure is 35psi, high side is about 210 (its was 100F in the shade). At idle, with a/c on max and fax on high I get about 55F air.. On the freeway I get 40F..

I'm thinking I may be slightly under charged..

Maniak, this is fyi so you can compare numbers:

I was getting 58 degF air on 85 deg ambient temp day at hwy speed...
....
added 12 oz. of R-134a...
....
now I get 40 degF air on an 85 deg ambient temp day at hwy speed...

I don't know if I'm still undercharged, but it's a lot better than it was.

 

[Glacier991]

I'd say you are right on with your charge. The VOV design was created to provide improved cooling at idle/low speeds.... whether it does or not is open to debate.