Dash AC not cold - have low/hi pressure gauge

[williams01]

2004 HR Ambassador - when engine running with AC on Max I’m getting Dual manifold gauge a negative 10 psi on low side and 100 psi on high side (90 degrees outside). Engine off after 30 min I’m getting 100 psi on low and 100 psi on high.

It’s the SCS system and says it holds 50oz of refrigerant.

I tried dumping 20oz can of r134a into it but no change in pressures.

Did start noticing icing in the TXV valve , but can’t say if it had been doing before refill. But def coming the elbow section of that valve at this point.

Can I keep adding r134 hoping it kicks the condenser on or do I risk damaging something? Is there a way to use gauges to avoid over fill?

 

Edited May 25, 2021 by williams01

[hermanmullins]

My advice is to take it to an Auto or RV shop and have it done by a professional. I went the DYI and wasted over $100.00 worth of R134A and still had to take it to  shop. Problem solved. And don't have a sticks and brick A/C tech work on it. They are great with Home A/C but not with auto.

JMHO

Herman

Edited May 25, 2021 by hermanmullins

[dickandlois]

1 hour ago, williams01 said:

2004 HR Ambassador - when engine running with AC on Max I’m getting negative 10 on low side and 100 on high side (90 degrees outside). Engine off after 30 min I’m getting 100 on low and 100 on high.

It’s the SCS system and says it holds 50oz of refrigerant.

I tried dumping 20oz can of r134a into it but no change in pressures.

Did start noticing icing in the TXV valve , but can’t say if it had been doing before refill. But def coming the elbow section of that valve at this point.

Can I keep adding r134 hoping it kicks the condenser on or do I risk damaging something? Is there a way to use gauges to avoid over fill?

 

Not a good idea to keep adding Coolant to the system without using a AC charging manifold. To easy to overcharge the system and cause some expensive repair bills!

You need to know if the low side of the system is creating a vacuum. Then one needs to know what the high pressure side is doing pressure wise !

Think it might be best to have an AC tech do the job, It is a lot different then adding a few ounces to a small Automotive system.

Rich.

[sstgermain]

What you need to do is bypass the low pressure cutoff to get the refrigerant cycling through the system then charge it with it running. Icing is generally low R134

Edited May 25, 2021 by sstgermain

[txiceman]

Best advice is to take it to a qualified shop.  Not knowing what you are doing can not only be costly, but dangerous.  Just adding refrigerant is not the fix.  You need the right instrumentation to properly diagnosis the problem.

Remember that the information and advise you get on the internet is worth exactly what you paid for it....nothing.  It take a lot to filter the useful information form the manure.  I have spent my career in industrial refrigeration as an engineer with many days in the field and still wind you getting help at times from the fellows that work on these units on a daily basis.

Ken

[wayne77590]

My coach is on a Freightliner chassis and I had basically the same problem - would blow hot air. I finally found a Freightliner dealer that added dye and looked for leaks. They found the leaks at the fittings.  Replaced and fixed.

As Ken stated, be cool, take it to a professional. It is not worth the aggravation you will go through by yourself and possibly never find the cause.

[williams01]

2 hours ago, sstgermain said:

What you need to do is bypass the low pressure cutoff to get the refrigerant cycling through the system then charge it with it running. Icing is generally low R134

How would one do that?

[williams01]

2 hours ago, dickandlois said:

Not a good idea to keep adding Coolant to the system without using a AC charging manifold. To easy to overcharge the system and cause some expensive repair bills!

You need to know if the low side of the system is creating a vacuum. Then one needs to know what the high pressure side is doing pressure wise !

Think it might be best to have an AC tech do the job, It is a lot different then adding a few ounces to a small Automotive system.

Rich.

Low pressure side is pulling vacuum @ -10psi / 100 psi for high side. I have a dual gauge to pull pressures.

[williams01]

Unfortunately it was a last minute breakdown, we leave Saturday for 2 months on the road. So was trying to troubleshoot at least prior to heading out. Got a Hi/lo gauge and was hoping it’d give me insight - I think it’s the TXV valve, anyone know how to test those 

[rayin]

Any automotive A/C shop can get it working again if their parking lot is large enough for your MH.

You can always run the genset and roof air conditioners. Adding refrigerant when un-needed risks destroying the compressor. If that happens you're going to be paying for replacing the entire system components, no amount of flushing will remove all traces of metal shavings and dust.

This might be helpful: https://www.btrac.com/documents/svc-manual-revision-i-feb-2011.pdf

Edited May 25, 2021 by rayin

[txiceman]

3 hours ago, williams01 said:

Unfortunately it was a last minute breakdown, we leave Saturday for 2 months on the road. So was trying to troubleshoot at least prior to heading out. Got a Hi/lo gauge and was hoping it’d give me insight - I think it’s the TXV valve, anyone know how to test those 

You need some training and instruments to properly diagnose a TXV issue.  Just get it to a local automotive shop.  Otherwise, you head off down the possibly expensive path of changing parts until you fix it.  To replace a TXV, you need to replace the valve, pressure test and then evacuate the system and then recharge with refrigerant.

Ken

[sstgermain]

7 hours ago, williams01 said:

How would one do that?

Clip lead across it

[williams01]

3 hours ago, sstgermain said:

Clip lead across it

Not doing this myself, having a trained mechanic take a look but I want to be able to have him check this. That at front of bus or back of it?

[txiceman]

The TXV is mounted at the evaporator coil.  The low pressure cut-out can be mounted anywhere in the suction line, but probably somewhere near the compressor.

Ken