Red Dot AC questions

[kfrosty]

First, does anybody have any pictures of the evaporator mounted without the armor plates? My evaporator is laying in the back with a lower bracket. I'm looking to see what others have done without armor plates. Or if the armor plates can be purchased, any insight would be appreciated.

Second, the condenser fans on top, when do they come on? The unit was installed when I got the vehicle but looks like the armor plates in the back were taken out and the condenser just laid in the bed. I've put 60 oz of R134A in and low side pressure is 80. Air is somewhat cool but not cold like I'd expect. Looking for that and any tips on troubleshooting these units.

Thanks

 

[NDT]

Your low side pressure is way too high. The condenser fans come on when the high pressure switch calls for them, because the high side is getting too high. If the install was done by someone else, and you do not know if it ever worked right, you better start at square one. Get a copy of the install instructions and make sure it is done right. Also, proper evacuation and oil charge is super important with 134. Do it over if there is any doubt.

 

[kfrosty]

Install I'm sure was done by the government. It was an armored vehicle so I'm going to surmise it had to work when installed. So maybe the sensors are bad and I ordered a couple.

Maybe the dryer is bad, ordered one of those as well. Still one of the questions remain, at what pressure do the condenser fans come on?

 

[infidel got me]

A/C

What is the high side reading? The low side is high if the compressor is not on, if it is not on that is a static reading. A lot can be told by having both the high and low side readings, and you really need both readings to properly diag. a/c. I would probably evac. and recharge the system for starters. Hope this helps.

 

[kfrosty]

High side is up and down. See it go as high as 375 and come back down to 300. The filter dryer is getting hot, really hot.

I'm getting a new filter dryer, trying to get a evacuator and then a vacuum pump etc, pull everything out, vacuum and start again. I'm guessing if the high side is hitting 375, then either the pressure switches are bad or the condenser fans aren't working.

 

[infidel got me]

You should be able to either hear or feel the condenser fans coming on, if not, that is a problem to start with. There should be a switch at or near the drier that you should be able to jump to see if fans power up. The drier on some systems will be hot to the touch-- it seems like it is usually on a add on a/c. On a regular a/c system, low side pressure should be 35 to 40 but not over and high side around 275.
Readings will vary depending on temp. and air flow across the condenser, I'm just trying to give a basic guideline. You are on the right track by evacuating/recharging system. Start fresh, then you take a lot of guess work out of the equation.

 

[kfrosty]

IGM,

Finally got the system vacuumed, changed out the dryer, vacuumed again. I added PAG 100 oil as I can't find any SP-15. I found a crossover link online, not sure if it's correct, but it recommended PAG 100 if changing to R134a and compressor indicated SP-15.

I then started charging, static pressure for some reason showed 70 on the low side. I let the freon load for a minute or so, compressor looked to kick on and low side is around 40. The high side slowly kept climbing. It got to 275 and the Condener fans didn't come on.

It's probably 68 outside and had rained on an off earlier. Humidity is 60+ I'm guessing.

It's cool outside but the air coming out of the inside vents feels pretty cold. The low side lines has a lot of condensation on them like you see on a AC working.

But maybe my hand was getting used to it but seemed like as the got around 250, the air wasn't as cool as it originally was. I'm going to try and find my heat laser and shoot the vent and see what it reads and it's of any help.

Going to try and jumper the switches on the dryer and see if that kicks on the fans. I'd still like to know the parameters of when the condenser fans should come on and when they go off.

 

[profo]

Usually the driers have a lil window on top that's usually cover with black paint its a lil circle I normally fill with Freon when compressor is pumping and fans are on till air bubbles in window stop then you stop adding freon also this will get you real cose to correct fill. You add a lil stop watch window add repeat. You can't just keep adding though cause expansion valve has to catch up with charge going through.

 

[kfrosty]

Ok, I installed a new condenser today and finally think I got the AC working. For anybody else interested, the condenser fans come on when the high side hit's 300, or at least on mine. Today in the 60's, raining outside, low side is around 40. Filled the freon up until the bubbles went away in the dryer glass.