GRRR! I've got black death!

[itsacrazyasian]

I just came back from looking at a fellow member's 6.9. Ran the AC the entire way back on 2nd fan speed (1st will freeze up otherwise for long periods). granted its only 80F and its night out, my accumulator was covered in frost to the point where i couldn't see black anymore. I was going to take a pic but my camera phone doesn't have flash to capture it. I don't think your bumper is the problem...

You are running electric fans?

 

[DaytonaBill]

Not yet, it's next on my list, though...

I'm moving to Houston this coming Wed and I will have a little time to get my self established and fans set up before it starts getting over 85° by middle of May...

But anyway, today I'm going to continue the farting until temps won't get any lower. Remember how my gauge adapters to the R-12 connectors leak? Well, I'm using the high side adapter, that's the one that leaks and what I have done is I wrapped the end with a paper towel all folded up and held in place with a twist wrapper. That way I can see if I'm letting the oil out and so far, the paper towel is still dry.

 

[itsacrazyasian]

Just for you DB.

You must be registered for see images attach

btw my low side pressure is 30 over 145

Thats at about 82-83 ambient outside air.

edit: Thats at IDLE. If i kick it off idle it'll drop into the low 20's.

 

[DaytonaBill]

Those are good numbers... You know, I was beginning to suspect that the recirculate door was allowing air in, because I farted gas out incrementally until low side pressures dropped down to 15 PSI (sometimes 5 PSI) and I reached the limit in that direction and added more to bring pressures back up to 25 PSI running around in 40 MPH traffic... At idle, it's around 35 PSI and the high is close to 150 PSI. Sometimes rises to about 190 PSI... I wouldn't be surprised if there was a little moisture with all of the hooking and unhooking the gauges I've done.

So yeah, after thinking about your numbers, I became totally convinced that the outside door was my problem...

I ran the gauges out into the cab, draped over the window... Just the low side hose was still connected. I wanted to see what it was doing and comparing that with the vent temps... Had the pressure so low (15 PSI) that it didn't take long for the frost to show up below the orifice tube, all the way into where it disappeared into the evap case...

BUT it never got below 44° at the vents and it was 79° today...

Sure, I think a fan would definitely help, but there's got to be another reason why I couldn't ice up the evaporator with the low pressures I had it down to... Not even a little frost except for below the orifice tube.

I'm beginning to suspect that the recirculate door is letting in a lot of warm air... That has to be the reason my evap never froze up at the pressures I had it down to... By the way, the test drives I take is about 7 miles and takes me more than 15 minutes to get back home.

So tomorrow, I'm going to take the fan motor out and see if I can fashion some kind of Styrofoam plug that I can stick in the hole...

That should help a lot... If not, then I'll just wait until I'm in Houston before I add a fan. The condenser is 24" x 16"... I'm hoping to fit a 16" fan in front of the condenser... If not, then I might go with two 12" fans... I'm going to relocate the power steering cooler so I can fit the other fan on the other side of that vertical bar in front of the condenser.

Anyway, At least I'm in the sweet spot as far as the refrigerant is concerned... I sure hope I'm done with that...

C-ya!

 

[itsacrazyasian]

Well i just wanted to post what my truck experiences. 29F air at idle is pretty good. 23 going down the road. Can't use the 1st fan speed or i will ice her up.

 

[DaytonaBill]

I'm jealous... ;p

How did you get your IR thermometer to take an accurate reading of your vent temps???

I've had a stick thermometer stuck in the same vent as the IR reading was taken from and the stick said 50° but the IR said 34.5°???

As a result with my IR thermometer's inability to take accurate readings of air, I use the outdoor - indoor thermometer thingy with the thermocouple stuck in the vent for temp readings...

I even had to paint my evap inlet and outlet with flat black (because it's shiny) in order to take IR readings (per instruction manual that came with IR thermometer)...

But I do appreciate you going through the trouble of getting those pressure readings and this proves to the other guys that there are alternative refrigerants that work as well as R-134a, or better, with lower head pressures. Just that alone shows that you can expect better MPG and increased compressor longevity through greatly reduced head pressures...

145 PSI @ 82° or 84° is easier on the compressor than 134a's higher pressure of 230 PSI @ 84° (That's 59% higher than Industrial 12a)...

A truck charged with 134a will never be able to get better MPG than an exact model charged with this refrigerant (Industrial 12a from Enviro-Safe Refrigerants, Inc) and for the tree huggers, it's also considered a "Green Refrigerant"...

Last year, I pulled a enclosed U-Haul trailer down from Asheville, NC to Daytona with the A/C on and got 17 MPG @ 70 MPH... Can anybody else do better than that? Before I replaced the entire system, I used to get 15 MPG under the same conditions and now I get 13% better MPG...

Thanks Itsacrazyasian for all of your help and encouragement in this project... It's been educational as well as entertaining...

 

[itsacrazyasian]

My IR gun gives me a good reading on whatever i have it pointed at. I aim at the back of the vent. The air is going to be as cold or colder then the duct surface since the air is absorbing heat from the surrounding duct. I can stick a probe style thermometer in it if you like. But i use the IR gun around the shop constantly and its very accurate.

 

[DaytonaBill]

Naw, that's ok... Mine has some design flaws... It's made by... Wait for it... CEN-TECH!!!

From my experience, I highly recommend staying as far away from this as you can...

 

[DaytonaBill]

Today, with mid to high 70s...

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

​

 

[itsacrazyasian]

getting better but not quite there. A electric fan will help boost airflow at lower speeds. What will she get down to if you kick it off idle? the other thing i see is your cycling switch. i have mine set to cut out at 22 psi. Look inside the switch once you remove the connector. 1/8th of a turn counter clockwise is 2 psi. This will keep it from kicking off the compressor when you're rolling down the road and it should be getting very cold. this stuff works at some funky pressures.

 

[RLDSL]

You don't ever want to use one of those suction screens on the back of your compressor. Install a proper filter in the suction side hose. Most reputable AC supply houses no longer even carry those suction inlet screens because they generally cause more damage than they could ever concievably prevent. THey clog up very quickly causing the compressor to suffer from a lack of lubrication and then they burn up. Since the pressure is not too lowm there is no auto shut down and you cook the thing. It does not cost that much more to have a proper filter installed in the line, or for that matter, if you are going to be installing two filters, you may be able to buy a crimp kit off ebay for what it would cost to have the filterrs crimped on . Call around first.

 

[DaytonaBill]

getting better but not quite there. A electric fan will help boost airflow at lower speeds. What will she get down to if you kick it off idle? the other thing i see is your cycling switch. i have mine set to cut out at 22 psi. Look inside the switch once you remove the connector. 1/8th of a turn counter clockwise is 2 psi. This will keep it from kicking off the compressor when you're rolling down the road and it should be getting very cold. this stuff works at some funky pressures.

I've got two cycling switches... The one I've been using lately is stuck closed (like it's jumpered...) and the other one is set for 22 PSI...

I think I need to fart just a little more and put a fan on the condenser. I installed new weatherstripping on the side of the recirculation door that flaps against the fresh air port. That was an easy job and shaved nearly ten degrees off the vent temp... I also fixed the vacuum hose to the motor that operates the recirc door... Now I just have to wait until I'm working after I move to Houston... At least I can stay cool without the fan for now... My high fan temp has dropped to 42°, my second fan temp is 35° and low speed gives me 28° and an iced evaporator (I can tell when it's frozen up, the temps starts climbing...) but it does take a little while to freeze up on low fan speed...

Here's some pictures from this afternoon... After repairing the recirc door, more white stuff from the orifice tube, all of the way to the suction inlet (except for the 'rubber' part of the hose) of the compressor !!!

This is from low fan speed...

You must be registered for see images attach

You must be registered for see images attach

This is from second fan speed...

You must be registered for see images attach

And my refurbished recirculation door...

You must be registered for see images attach

You must be registered for see images attach

And the key to taking the door out...

You must be registered for see images attach

 

[DaytonaBill]

You don't ever want to use one of those suction screens on the back of your compressor. Install a proper filter in the suction side hose. Most reputable AC supply houses no longer even carry those suction inlet screens because they generally cause more damage than they could ever concievably prevent. THey clog up very quickly causing the compressor to suffer from a lack of lubrication and then they burn up. Since the pressure is not too lowm there is no auto shut down and you cook the thing. It does not cost that much more to have a proper filter installed in the line, or for that matter, if you are going to be installing two filters, you may be able to buy a crimp kit off ebay for what it would cost to have the filterrs crimped on . Call around first.

Hi RLDSL! I ended up not using those filters... Itsacrazyasian told me the exact same thing and it sounds like you guys are right... Oh well, I'm out only ten bucks...

I can always stick them in my nostrils if I ever get caught outdoors in one of those sand storms they call a Haboob...

RLDSL, later on this year, I'm going to install rear air conditioning using your write up and so I will be getting a crimp set... But not anytime soon... Do you think a used set would be the way to go? I'm only going to do this once... Thanks...

 

[DaytonaBill]

Well, here we are, months later and I've moved to Houston and then to Nashville...

Never did get to do the electric fan thing and my A/C is still a tad too high on the pressures... I had planned to get the fans and fart out just a little gas and then everything should be good to go... Well other than insulating the cab, new weatherstrips and insulating the airbox...

Anyway, I've been very pleased with the performance of the A/C so far...

June 27, I got 48° out of the vents on high fan speed @ 105° temps... It took about 7 miles at freeway speeds to get there, but that's a 57° drop from ambient temps... It seems that the propane blend works better in heat waves than I expected...

And we still have July, August and September to go. Heh...

I can't wait to get e-fans and fart some gas out, then at last, I'll be driving a meat locker...

 

[itsacrazyasian]

your pic of the accumulator looks exactly like mine on the drive home from work. Even when it was 103 out the other day.