AC pressure

[texasvet54]

I have a 220VAC Ocean Breeze air conditioning system on my Three Buoys houseboat. The system uses R-22.

My coils are icing up indicating that I am low on refrigerant. My gauges tell me that my pressure is low at about 50 lbs on the low side instead of 70. When I add some R-22, the evaporator coils lose their frost, but the pressure doesn't go up. I don't want to add any more R-22 as this stuff is expensive. I did go so far as to add R-22 for about 20 seconds and there was no change in the pressure. It stays at 50.

So, what can I do to get my low side pressure back to normal, around 70lbs, and stop the icing?

Thanks,
John

 

[dwco5051]

Re: AC pressure

The first thing to check is that you are getting enough air flow across the coils. Clogged filters, dirty fan cage, coils dirty or partially clogged, bent fins on coils, etc. ACs are not designed to lose refrigerant. If it actually did need more gas than adding more is only a temporary fix.

 

[Tim Frank]

Re: AC pressure

My coils are icing up indicating that I am low on refrigerant.

No. Coils can ice up for a lot of reasons.

My gauges tell me that my pressure is low at about 50 lbs on the low side instead of 70. When I add some R-22, the evaporator coils lose their frost, but the pressure doesn't go up. I don't want to add any more R-22 as this stuff is expensive. I did go so far as to add R-22 for about 20 seconds and there was no change in the pressure. It stays at 50.

So, what can I do to get my low side pressure back to normal, around 70lbs, and stop the icing?

Thanks,
John

Diagnose the problem properly or get a professional in to do it.
Ramming more refrigerant in without actually knowing what is going on ...i.e. just for giggles, can damage the compressor pretty quickly.

What is the high side pressure? Did you measure that?
Given that the filters etc. are not a problem per post#2, the next thing I'd look at would be the TEV.

 

[texasvet54]

Re: AC pressure

Thanks for all of the replies. I spoke to an Ocean Breeze rep. He told me that adding R-22 and not seeing the low pressure side rise is very odd. I think I'll have a vacuum put on the system, repair any leaks and fill the system with the 4 lbs. that he suggested or until the system is normal.

Texasvet

 

[Tim Frank]

Re: AC pressure

If it were me, I'd diagnose the problem properly first.

1) You can't put the system under vacuum and then find a leak....well, I guess you can, but it would be better and easier to check for freon leaks first. Then, if there`are no leaks you haven't wasted the time pumping down the system and evacuating it.
2) The fact that you added freon with no results should point you in a different direction.
3) Did you clean the components as suggested? Do you know what the head pressure is?

 

[texasvet54]

Re: AC pressure

I forgot to mention that I started looking at the low side pressure at the end of last summer and it hasn't changed. So, I'm not suspecting a leak. Also, if there is a high pressure valve, I don't see it

So, I'm left with a unit that is putting out 50 to 55 air, depending on the ambient air, with a low pressure side that doesn't want to cooperate.

Texasvet

 

[Tim Frank]

Re: AC pressure

I forgot to mention that I started looking at the low side pressure at the end of last summer and it hasn't changed.

My gauges tell me that my pressure is low at about 50 lbs on the low side instead of 70

So why do you think that 70 PSI is "correct"?

Were you having icing problems last year when you "started looking at this"?

 

[glenn property of pam]

Re: AC pressure

you haven't installed a heap filter or something else that is reducing air flow have you

 

[texasvet54]

Re: AC pressure

So why do you think that 70 PSI is "correct"?

Were you having icing problems last year when you "started looking at this"?

Yep, it's been icing half of the coils back from the low pressure port since I bought the boat, almost 3 years ago.

As far as the 70 psi reading, that would give me about a 40 degree coil with R-22. Right now I've got a 24 degree coil as far as I can tell on my old gauges.

Texasvet

 

[texasvet54]

Re: AC pressure

you haven't installed a heap filter or something else that is reducing air flow have you

Nope, no HEPA filter installed, just a simple paper filter.

I did remove the filter and I used two circulating fans to increase the air flow across the coils as a test. The pressure didn't change a bit.

texasvet

 

[bigdee]

Re: AC pressure

Since you do not have a gauge port on the high side your only option is to evacuate the charge and weigh in the correct charge. If the coils still ice up you may possibly have restriction in the capillary tubes or a bad compressor. Have you measured the heat at the inlet side of the condenser coil? You can calculate that into a pressure.

 

[texasvet54]

Re: AC pressure

Since you do not have a gauge port on the high side your only option is to evacuate the charge and weigh in the correct charge. If the coils still ice up you may possibly have restriction in the capillary tubes or a bad compressor. Have you measured the heat at the inlet side of the condenser coil? You can calculate that into a pressure.

I've measured the temp of the return air if that is what you mean. It's around 75 and the air coming out of the vent is around 55 or a little lower. So I've got the 20 degree difference that is looked for. Maybe I should just leave everything alone at this point until I have a hard failure.

texasvet

 

[hrdwrkingacguy]

Re: AC pressure

The heat at the inlet side of the outdoor coil on the air side is ambient temperature, the heat on the refrigerant side entering the outdoor coil is discharge line temp(discharge temperature + heat of compression)...Neither of which without pressure tell you anything...Rule of thumb on a cap tube system is the suction line should be closer to 0 degrees superheat as the ambient temperature goes up over 100 degrees...the discharge line shouldn't be over 190 or 195 or your going to trash the compressor...So low pressure, high superheat, hot discharge line points to an indoor coil or low side problem...