Ultimate AC Line Construction Tutorial - HalfSpec Engineering

[halfspec]

Have you checked Vintage Air for the pressure switch that screws into the dryer?

I think David's already bought his switch. But it may be a good idea for future builders. It's been a couple of years since I combed through their catalog. Back then they didn't have anything compatible with the dryer I use in this tutorial. My drier uses a 10mm schrader fitting. I chose it because that's exactly the fitting GM uses on their camaros/corvettes AC hardlines. That's how my drier can support the use of fbody AC pressure sensors directly. It does make using pressure binary/trinary switches difficult though as most aren't made for the rare'ish 10mm schrader.

Lane
 

[Cobranut]

Yep, I just ordered the switch today.  Since the connectors from Mouser were so cheap, I went ahead and ordered those as well.  If it ends up needing a different connector I'll post back here and let you guys know.

Thanks for all the help guys.    
I'll probably have more questions in the next few days.  I'm trying to make as much progress as possible while I'm home next week. 

[Cobranut]

Here's the switch.
Does this look like the Metripac connector will fit?

Thanks,
David

[attachimg=1][attachimg=2]

[Cobranut]

The connectors were in the mailbox. 

Doesn't fit, damnit. 

Anyone else have an idea what connector fits the above switch?

Thanks,
David

[halfspec]

The connectors were in the mailbox. 

Doesn't fit, damnit. 

Anyone else have an idea what connector fits the above switch?

Thanks,
David

From memory the pressure sensor connection looks right / like it did when I bought them. Are you sure you ordered connector housing 829-12052641?




They key / cutout in the diagram above is what gets around the bulge inside the pressure sensor connector. It's not shown in the 3D purple drawing above, but it should be designed into 829-12052641.

Lane

[Cobranut]

OK, I opened up the connector package and tried it.
It does fit, albeit tightly, but will do the job. 

That connector looks like it really needs a tab instead of the bulge. 
I can trim the edges of the slot a bit to make it slide in easier. 

Thanks Lane,
Sorry I doubted you.

David

[halfspec]

That connector looks like it really needs a tab instead of the bulge. 

Agreed. I do think there is or at least was a Metripack 150 connector that fit the bulge better. I just haven't been able to find it. As is, the connector locks to the sensor correctly and the electrical connection is very good, so I never got too obsessed with optimizing. A tight fit is a good fit when it comes to sealed electronics. I wouldn't trim anything

Lane

[Cobranut]

Finally got the car running and driving.
Now my A/C works when the engine is cold, but once everything is warmed up under the hood the pressure switch won't close to start the compressor. 
If I jump the switch it works and cools reasonably well. 
I can't imagine the static pressure is going above 455 and opening the switch when it's hot, but it sure seems like that's whats happening.
Anyone else had a similar problem?

Thanks,
David

[halfspec]

Finally got the car running and driving.
Now my A/C works when the engine is cold, but once everything is warmed up under the hood the pressure switch won't close to start the compressor. 
If I jump the switch it works and cools reasonably well. 
I can't imagine the static pressure is going above 455 and opening the switch when it's hot, but it sure seems like that's whats happening.
Anyone else had a similar problem?

Thanks,
David

I would recommend putting a manifold gauge on the high and low side and get real feedback on what's going on, otherwise you'll just be making educated guesses. If you're dealing with a pressure spike on the high side, you'd see it in the gauges.
A high side pressure problem is probably related to a clogged expansion valve.

Lane

[Cobranut]

Finally got the car running and driving.
Now my A/C works when the engine is cold, but once everything is warmed up under the hood the pressure switch won't close to start the compressor. 
If I jump the switch it works and cools reasonably well. 
I can't imagine the static pressure is going above 455 and opening the switch when it's hot, but it sure seems like that's whats happening.
Anyone else had a similar problem?

Thanks,
David

I would recommend putting a manifold gauge on the high and low side and get real feedback on what's going on, otherwise you'll just be making educated guesses. If you're dealing with a pressure spike on the high side, you'd see it in the gauges.
A high side pressure problem is probably related to a clogged expansion valve.

Lane

Thanks Lane,
I'll try to put gauges on it this weekend. 
It seems to be more temperature related though, as it doesn't even try to enable the a/c once the engine is warmed up.

[Cobranut]

Lane:

I put the gauges on it today.
Relatively cool engine, Lowside and Highside =90psi
Started the engine, A/C Compressor would not engage.
Jumped pressure switch, A/C came on and pressures stabilized around 25psi lowside and 175psi highside.
These are well within the range for this switch.

Looks like the pressure switch I got from Ryder is defective. 
I'll check my receipt and see if they have a warranty.

Thanks for the help,
David

[Exidous]

So I was finally able to get my A/C to run how I wanted. I had made three mistakes after talking with the A/C guy a friend recommended.

First, the PAG 150 oil is meant for a GM setup with an orifice tube. PAG 46 would be more appropriate since we are using a TEV.

Second, 8oz of oil is just too much for our setup. 3-4oz is more appropriate since we are not running the enormous receiver/dryer of an orifice tube system.

Third, due to the excessive oil you are not able to run as much r134a. After the lower oil I was at 1lb, 12oz with a 30psi low and 275 high with the doors open and about 54°F  out of the vent. It was 90+ outside and the car was stationary. Sitting with the doors closed the TEV opened up and high side dropped to 240-250 and the vent temp was 46°.

Hopefully this will help some folks that are in hotter climates and need every degree they can get.

Patrick

[Skeltic]

Cobranut, I have gone though 3 switches that only worked the first time i turned on the ac. I just run with it jumped. I am paying attention for an answer.