A\C Retrofit parts
06-27-2012, 03:53 PM
#11
Originally Posted by unit505
On the subject of AC's and orifice tubes, I don't know if this problem exist in the pick ups or not, but.....We're having AC issues with our E250 and E350 ambulances. At low speed driving around town (under 70mph) the AC's work great on all of them that we've serviced. Above 70mph, the temp jumps up pretty quickly and the heat sets in. We were told yesterday by the dealer to change the orifice tubes to the Chevrolet white orifice tubes (I believe it was the white ones). Something about the Ford tubes being a Super High Pressure orifice tube and the Chevrolet being a standard high pressure. The Chevrolet tube is suppose to allow more flow. They told us that this would give us better overall pressures at high rpm and cool better. It doesn't make sense to me since higher speed should push more air through the condenser resulting in cooler temps using standard orifice tubes, but the dealer said that the whole ac system doesn't make sense on the vans in terms of the way they operate since the rear AC operating off of the same compressor cools better than the cab. We're going to take one of our highway vans (Out of town truck) and try the Chevrolet Orifice Tubes and see if it really cools better at higher speeds. If it works, we're going to make the change in all of our larger highway units and keep the factory setup on the in town units and hope that we don't have to use a highway truck in town or an in town truck on out of town runs.
As soon as the mechanic makes the swap on one of these, I'll let you know what the result is.
As soon as the mechanic makes the swap on one of these, I'll let you know what the result is.
06-27-2012, 06:48 PM
#12
Salvage Yard Pro
That's basically what I got out of the conversation. The Chevrolet orifice tube is suppose to allow more flow, hence less load on the compressor. I haven't had to work on my 94 ac since it cools like a deep freeze and haven't had the funds to replace my compressor in the 95. When I do get the compressor replaced, I'm going to look into the orifice tubes that are available. 95% of my mileage is highway at 70-80mph and if a simple change in orifice tubes could enhance the ac operation and load on the engine, I may pull the Chevy orifice tube swap. We're currently moving the ambulance maintenance shop to a new larger building, so it may be a couple of weeks before I get to see the results. Very interested to see the outcome.
07-03-2012, 05:03 PM
#13
Salvage Yard Pro
Update.............I was told that we lost two ac compressors that had both been fitted with the Chevy Orifice Tubes. I don't know what went bad on them, but I do know that they failed. Scratch that idea. The dealer has sent a letter to Ford Factory Techs requesting some other explanation for the change in cooling ability above a certain rmp or speed. Two highly regarded AC shops and the issue cannot be identified.
07-03-2012, 07:51 PM
#14
Springer Spaniels Rule
Thread Starter
The problem with the gm tubes is the orifice is too small which builds up too much pressure in the compressor, overloading and stressing the compressor causing it too fail.
07-04-2012, 04:58 PM
#16
Salvage Yard Pro
I'll ask the mechanic tomorrow. I'm in one of those trucks today! Freeze you out at idle and blowing at 85 degrees at 60 - 70mph. This sucks. It starts warming up at around 1900 rpm and gets really warm around 2300rpm.
07-05-2012, 12:54 PM
#17
Salvage Yard Pro
Another one bites the dust! Ac just went kaboom! Gotta get this truck back to the shop and see if the line blew or the compressor. Pretty impressive bang with the sound of shrapenal flying all under the hood. Freon everywhere!
07-05-2012, 01:43 PM
#18
Hi-Rev Motorsports
weird... sounds like the liquid is either getting back to the pump or pressure is very high... in which the high pressure cut out should have turn it off (if it had one)
I would say you need to hook up high and low side gauges and drive it and see whats going on...
I know on my truck high side pressure stays the same from 1500rpm to 3500rpm and it doesnt get warmer...
there is a point where the compressor is most effcient and thats at a certain engine rpm and it cools the best but above that it cools but not as fast but its just the same as being under rpm...
the critical fill is very important. I set mine up different than most people. I set mine up at 70-75F outside (ambient) temps and run the engine to 2500rpm and fill it just until the compressor stops cycling... not a tad more. then I drive it and run 65mph and see if it cycles... if it doesnt its good if it does I add a tad more...
this results in the coldest AC possible...
I;ve had no issue hitting 28°F out the vents (ICE Cold) with this charge even on worn set ups
I would say you need to hook up high and low side gauges and drive it and see whats going on...
I know on my truck high side pressure stays the same from 1500rpm to 3500rpm and it doesnt get warmer...
there is a point where the compressor is most effcient and thats at a certain engine rpm and it cools the best but above that it cools but not as fast but its just the same as being under rpm...
the critical fill is very important. I set mine up different than most people. I set mine up at 70-75F outside (ambient) temps and run the engine to 2500rpm and fill it just until the compressor stops cycling... not a tad more. then I drive it and run 65mph and see if it cycles... if it doesnt its good if it does I add a tad more...
this results in the coldest AC possible...
I;ve had no issue hitting 28°F out the vents (ICE Cold) with this charge even on worn set ups