Tn75s air conditioning relay

[LouNY]

Again with the tractor running I opened both manifold valves and the low side went to 175 and the Red High side dropped to 190.

Never open both valves on a charged system.

OK, step one.
all the gauge set ups I have used when checking your pressure the manifold valves are CLOSED.
With the valves closed the lines feed to the gauge but not into the manifold.

With the tractor shut off, connect your gauges to the correct fittings on the system leave the manifold valves closed, at this time you should have the same pressure indication on each gauge, this is your static pressure.

Start the engine and turn on the AC DO NOT OPEN the manifold valves, now you are reading the operating system pressures.

The ONLY time you should open the manifold valve(s) are when adding freon or pulling a vacuum on the system.

When adding Freon only open the LOW side valve to draw from your source into the low side of the system.

The only time to open the HIGH side valve is when evacuating the system or when pulling the vacuum.

Here is a link to a U tube video on using the gauges and manifold, I did not watch the entire video but it seems to explain the proper use of the gauges and manifold.

 

[jammer48]

Never open both valves on a charged system.

OK, step one.
all the gauge set ups I have used when checking your pressure the manifold valves are CLOSED.
With the valves closed the lines feed to the gauge but not into the manifold.

With the tractor shut off, connect your gauges to the correct fittings on the system leave the manifold valves closed, at this time you should have the same pressure indication on each gauge, this is your static pressure.

Start the engine and turn on the AC DO NOT OPEN the manifold valves, now you are reading the operating system pressures.

The ONLY time you should open the manifold valve(s) are when adding freon or pulling a vacuum on the system.

When adding Freon only open the LOW side valve to draw from your source into the low side of the system.

The only time to open the HIGH side valve is when evacuating the system or when pulling the vacuum.

Here is a link to a U tube video on using the gauges and manifold, I did not watch the entire video but it seems to explain the proper use of the gauges and manifold.

Wow Lou Thank you! I will get to this in the next day or two and report back... I am feeling a bit under the weather. I am determined to get this right.

 

[nyone]

I put freon in and touching the evaporator I had cold going in to touch and warm to touch coming out

It sounds like the system is working. Maybe not working well but working. Are you sure the evaporator and condensor are clean and clear? Can you see light through them?

 

[5030]

Everyone that's willing to learn or do things them self is in over there head at some point. It's how you get out of it. If your going to smack every project with your check book you will never learn anything.

OP AC in this and vehicles arnt very hard to work on. We just need a few key questions awnsered.

Over your head with an ac system can result in very expensive component replacement. Usually leaks can be attrobuted to charge valves not seating properly.

 

[nyone]

Over your head with an ac system can result in very expensive component replacement. Usually leaks can be attrobuted to charge valves not seating properly.

I have also had compressor seals leak and condensers have holes that where 2 weeks old. In fact I replaced the condensor 3x on one vehicle in 1yr. Finaly figured put that out of the box they had multiple pin holes. Could be a million reasons for a leak.

I have a leaking service port on a vehicle I'm driving right now. The cap holds pre pressure all year.

 

[5030]

...and for some reason AC techs fail to replace the caps when servicing them. Sort of like valve caps on tires....

 

[jammer48]

It sounds like the system is working. Maybe not working well but working. Are you sure the evaporator and condensor are clean and clear? Can you see light through them?

No both are extremely dirty... I am working with basicly one arm... shoulder surgery
in 10 days... trying to get this all done before surgery.

 

[5030]

You will find that the cost of relay's at your dealer will most likely be 4-5 times the cost from an electrinics supply place like Digikey or Dell Electronics. Not Dell computers FYI. My relays were 85 bucks per from the dealer and I crossed the catalog number at Digikey and got the same exact relays for 8 bucks each. I bought a few extra, just in case.

Pays to shop around on some stuff.

 

[jammer48]

Never open both valves on a charged system.

OK, step one.
all the gauge set ups I have used when checking your pressure the manifold valves are CLOSED.
With the valves closed the lines feed to the gauge but not into the manifold.

With the tractor shut off, connect your gauges to the correct fittings on the system leave the manifold valves closed, at this time you should have the same pressure indication on each gauge, this is your static pressure.

Start the engine and turn on the AC DO NOT OPEN the manifold valves, now you are reading the operating system pressures.

The ONLY time you should open the manifold valve(s) are when adding freon or pulling a vacuum on the system.

When adding Freon only open the LOW side valve to draw from your source into the low side of the system.

The only time to open the HIGH side valve is when evacuating the system or when pulling the vacuum.

Here is a link to a U tube video on using the gauges and manifold, I did not watch the entire video but it seems to explain the proper use of the gauges and manifold.

ok here is what I got:

static 135 low and 140 high
after start 50 low and 250 high

this was with an ambient temperture of 95 in the sun

temperatures to touch:
- Drier both sides hot to touch
- Condenser Warm in and hot out
- compressor Hot on high side and cold on low side
- between evaporator and expansion valve or the outside of the expansion valve cold and cold
- on the in side of expansion valve hot and cold

what do you all think? It's still blowing warm air but everything in cab hanging down is sweating.

No matter what I have to change the dryer for sure and i am yet to clean the evaporator and condensor. gonna do that later tonight when it cools down.

another interesting point..i tried to put a little refrigerent in but it wouldn't go in?

 

[Harry in Ky]

Keep at it, you'll get there. For openers, your static pressure should closer to 75 - 80 PSI on a hot day. Your pressures indicate an overcharge condition. How much refrigerant did you put in? Just guessing I'd say a TN cab system will take just over two pounds. The high pressure will vary more based on a number of variables, but the low side even on a hot day shouldn't be over 25 PSI. In fact I've seen systems work perfectly well between 15 and 20 on the low side. Wide open throttle. I don't bother with reading pressures at low RPM.

Why didn't you change the drier before you went to all this trouble? Replacing that is pretty much a given whenever you open up a system that hasn't been apart in a long time.