What's new
By:
Filters

AC experts step in

Remove dash, replace all blend doors. unfuck your hot wired heater. convert back to mechanical fan.
 
Put gauges on it and watch what the pressures are doing when the compressor turns on and off.
 
The pressures are a bit high... I know you converted to e-fans, but have you tried adding a small pusher fan directly on the condenser that is activated by the A/C switch? I have done this to many vehicles in the southwest to improve upon their A/C performance. Not enough to block a majority of the surface, just a little one up on the top corner where the charge initially enters to speed the cooling process.

I do believe you have other issues, though.

Another crazy idea I have floated in troubled R12 conversions is to add a second condenser in front of the first... plumbed into the rear one first, then out of the rear and into the front one, then out to the accumulator/dryer. Only requires some simple spacer fab and longer bolts, with the addition of one custom high pressure hose between the two units. This would add a shit-ton of capacity to the system, while cooling the refrigerant back close to ambient before entry into the orifice tube.
 
DRTDEVL said:
The pressures are a bit high... I know you converted to e-fans, but have you tried adding a small pusher fan directly on the condenser that is activated by the A/C switch? I have done this to many vehicles in the southwest to improve upon their A/C performance. Not enough to block a majority of the surface, just a little one up on the top corner where the charge initially enters to speed the cooling process.

I do believe you have other issues, though.

Another crazy idea I have floated in troubled R12 conversions is to add a second condenser in front of the first... plumbed into the rear one first, then out of the rear and into the front one, then out to the accumulator/dryer. Only requires some simple spacer fab and longer bolts, with the addition of one custom high pressure hose between the two units. This would add a shit-ton of capacity to the system, while cooling the refrigerant back close to ambient before entry into the orifice tube.
Click to expand...

Not a bad idea. Would have a ton of capacity when in slow traffic. Plumb it to the front condenser first.
 
BIG-O said:
Not a bad idea. Would have a ton of capacity when in slow traffic. Plumb it to the front condenser first.
Click to expand...

I thought about that, but I say rear condenser first. That way, the air hitting the rear condenser isn't heated up as much by the front condenser. In my mind, I would think it would cool better this way.

Basically, the rear condenser would do about the same as it does now, but with marginally reduced performance. The front condenser would then take the mostly-cooled refrigerant and bring it back down almost to ambient before re-entering the engine compartment.
 
40-50psig is too high.

If you have an orifice tube, you have an accumulator,not a dryer, similar but they work differently. The pressure cutoff switch should be mounted on the accumulator. Under the plug there is a slotted screw head. This is the cutoff adjustment. (if there is no screw head, you have a newer model is non-adjustable- these suck) Using your pressure gauge, raise the rpm to 1200 or so and adjust the cutoff for about 30 to 32psig. This will do wonders. 28psig will hang icicles and freeze the evap on a humid evening. Been there.

--12 years working in a Ford HVAC lab testing all the Ford HVAC parts as well as competitor's parts.
 
Tiha said:
What engine rpm are you taking your temp and pressure readings at?

ideally 1200-1500 rpm.

And you are trying to cool a big cabin, but any AC system should put out vent temps 30 degrees below ambient. From the factory they were designed to only be 20 degrees below ambient.
Click to expand...

That is correct. 20° to 30° below ambient
 
eraser5 said:
--12 years working in a Ford HVAC lab testing all the Ford HVAC parts as well as competitor's parts.
Click to expand...


Cool, You guys really fucked up with the eatc system on the panther chasis. Your blend doors suck balls.
 
eraser5 said:
40-50psig is too high.

If you have an orifice tube, you have an accumulator,not a dryer, similar but they work differently. The pressure cutoff switch should be mounted on the accumulator. Under the plug there is a slotted screw head. This is the cutoff adjustment. (if there is no screw head, you have a newer model is non-adjustable- these suck) Using your pressure gauge, raise the rpm to 1200 or so and adjust the cutoff for about 30 to 32psig. This will do wonders. 28psig will hang icicles and freeze the evap on a humid evening. Been there.

--12 years working in a Ford HVAC lab testing all the Ford HVAC parts as well as competitor's parts.
Click to expand...

You really got my interest now. Before I play with this I would like to understand what I'm doing.

First, I do have an orface tube and I did mis name the accumulator. The accumulator does have a cut off switch and I pulled the plug and it does have a slot screw under it. So far so good.

Now what I don't get is the orface tube is before the evaporator, but the low side service port is in between the evaporator and the accumulator. So how is adjusting something after the service port going to change the pressure. (Unless the accumulator is a restriction) When you adjust this, are you adjusting the cut off? That doesn't seem possible. When you say adjust it to 30 psi., I have to ask, doesn't the compressor shut down when this is unplugged? Do I adjust it alittle and then plug it in to check what I did?

I guess the main question I'm asking is what does this screw do?
 
WaterH said:
You really got my interest now. Before I play with this I would like to understand what I'm doing.

First, I do have an orifice tube and I did miss name the accumulator. The accumulator does have a cut off switch and I pulled the plug and it does have a slot screw under it. So far so good.

Now what I don't get is the orifice tube is before the evaporator, but the low side service port is in between the evaporator and the accumulator. So how is adjusting something after the service port going to change the pressure. (Unless the accumulator is a restriction) When you adjust this, are you adjusting the cut off? That doesn't seem possible. When you say adjust it to 30 psi., I have to ask, doesn't the compressor shut down when this is unplugged? Do I adjust it a little and then plug it in to check what I did?

I guess the main question I'm asking is what does this screw do?
Click to expand...

The two ports on a vehicle are compressor in and compressor out, or suction and discharge. I really really wish there was a port at the condenser outlet too. Condenser out sub-cool is the best way to set a charge level, but that would add 5 cents to the cost. No go!

Yes. Trial and error. Plug in, check pressure. Unplug, adjust. Rinse and repeat. You really need a thermometer poking into a center vent to check the temperature. Also, get your water hose and trickle water over your condenser so things do not over heat and over pressure while working. The pressure cutoff is factory set to R12 and 40psig was great for R12. Now that you have R134A, you need a lower suction pressure. Lower suction pressure equals lower evap out pressure equals more heat being sucked out of the air passing through the evap.
 
Back the screw out about half a turn for starters, if I remember that is pretty close.

Since the system is charged, maybe overcharged you may not notice a difference.

You said the compressor is cycling. So what low side pressure does it shut off at?
This will keep it running if the low pressure switch is shutting it off.

If you are over charged or pressure is too high the inlet of the evap is not as cold as the outlet. Meaning it is pushing through the evap too fast and the accumulator is colder than the inlet of the evap.
 
crisbee1 said:
Cool, You guys really fucked up with the eatc system on the panther chasis. Your blend doors suck balls.
Click to expand...

Yea, that was the "other" lab. The Schmucks in schmocks. We tested all the "wet" stuff. Radiators, heater cores, compressors, hose material, etc. As well as fuel rails. We froze, we heated, we hydro pressurized until burst, performance tested-liquid side, flow tested-air side, tested to failure. In other words, I got to tear stuff up on purpose! It was a great job. Then the plant closed. Sad day.
 
If your compressor is cycling with AC on max, meaning it is tripping the low pressure cutout, then that means you are still not fully charged. That would make your pressures even higher when done.

That chart is a great reference but again it is just a guide, it cannot account for airflow across the condenser or humidity in the air, all of the local variables.

and on top of that, they don't need to be that high, it is not normal, Maybe in a text book but not the real world. The higher the pressure the harder it is for everything to work correctly.

When we started doing conversions we were told "yeah you will see high pressures" and we did. We had some systems that operated amazingly at 400 psi. But the compressor wouldn't last a month.

Then we learn how to make it better.
 
Tiha, I blew up a lot of parts to make things better. A few not in a fun way.
 
eraser5 said:
Tiha, I blew up a lot of parts to make things better. A few not in a fun way.
Click to expand...

I bet that was a blast.
We were adding high pressure switches, trinary switches, electric fans. All kinds of stuff but I will never forget watching that needle approach 375 and just wondering what will blow first. Compressor groaning. Just waiting for it to lockup or clutch to start slipping.
Surprising enough we never blew anything but compressor. Had a couple rusty condensers that were probably leaking before we charged it.

LOL crazy stuff. Don't miss those days.
 
Tiha said:
If your compressor is cycling with AC on max, meaning it is tripping the low pressure cutout, then that means you are still not fully charged. That would make your pressures even higher when done.r.
Click to expand...

Ahh, this is the miss understanding. My compressor is not cycling. Meaning it never trips the low pressure when it's hot out. (It stays on) So adjusting this will not make a differnce right now? Correct? That makes more sense to me. I couldn't understand how adjusting this was going to lower my pressure.

So your sugesting I recover some freon till it starts tripping? Then adjust it to 30 psi.?
 
So I hooked up the gauges and put the plate in the throttle (1200rpm) They read 45-50 low and 175 high. It was about 90 out. I recovered freon untill the low side got down to 25 psi. The clutch still never cycled off. The high side was 150. I pointed a lazor temp at the accumulator and it read 34 degrees. I thought I must be getting somewhere. I've never seen it that low, so I stopped and removed everything and went for a drive. About five miles and the vent temp never got below 59. So I guess tomarrow I recover some more. I wish I had my scale to see how much I'm taking out. (The scale is at my restaurant)

Do you think I should keep removing freon untill the low side cut off?
 
It would be really nice to know the evap inlet temp.

You just need to take a reading from the pipe after the orifice tube as close to where it enters the heater box as possible.

That is a large amount of temp loss in the vents. There has to be heat intrusion from somewhere. Something strange is going on there.

You won't gain anything by taking more out of the system.
 
Actually where are you measuring the accumulator temp at? Can you measure the inlet vs the outlet?
if it is plugged it will act like a orifice tube and gets cold after the restriction
 
Tough to measure the inlet temp because it's right next to the headers. Plus the temp bulb on my AC multimeter quit working.

As far as the accumulator, I just pointed the lazor temp gun at the top. Could it be plugged? It's relatively new. (Replaced when I did the condenser) I don't think it's plugged because the low side service port is between the evaporator and the accumulator. If it were plugged, the low side would go up.
 
Just a quick up date.

i got a new evaporator and dryer. I was removing the old stuff tonite and found a bunch of junk on the orface tube. The condenser is a week old, so either the junk was allready there or my compressor is failing. I wish I had checked the orface when I changed the condenser. I guess I'm going to install the new stuff and see what happens.

About two two years ago when I changed the condenser to the newer style I changed the orface. It had a bunch of junk on it. So I put a new one in and ran it for a few days. Than I pulled it again and it was almost clean. I figured the junk was from a previous compressor failure. Now, I wonder if the current compressor is failing or if this is just junk that came out of the old condenser after a while.

Im coming to the conclusion that you should change every F'ing thing when you have a problem.

Anyways, tomorrow I should get it back together. I give an up date in a few days.
 
So it's back together and charged up. Took it for a ride and saw 52 degrees while driving. That's the lowest I've ever seen on this truck, but I didn't go till late afternoon and it was probably only 85 out. I'll try it again when it's 95 tomorrow. The temp goes quickly over 60 when stopped.
 
Another up date,

it was working fairly good, but still nothing to write home about. Last week I was parked (waiting for the wife) and the AC clutch started smoking. I said F it and got a new compressor, accumulator and orface. Took it all down and flushed it. Put it back and charged it. Now it finally cools decent. If I start it up, it makes cool air in seconds. Driving down the road or even just reving the engine, it blows air in the forty's.

The funny thing is the old compressor is not shot. It still turns and you can feel the pumping action. But obviously it was the problem. It sure is nice to turn down the fan after ten minutes. (Too cold)

thanks to all that helped
 
You must log in or register to reply here.
Top Back Refresh