HVAC-Talk: Heating, Air & Refrigeration Discussion banner
Cancel
Create thread New Forums

Frosted Suction Line ???

Jump to Latest
1 - 20 of 32 Posts
E

epacertified

· Professional Member / AOP Pro
Joined
·
5,109 Posts
Discussion starter · #1 ·
I would think by now that It would not be easy to confuse me but-----
Customer called husband up early leaving on a buisness trip
A/C not coolig - Suction line iced over!!!
Cant get there till noon so ---
Now when I get there system has had time to thaw

I start it up --Clean filter ---- fan running seems like good air flow
gauges show lower than normal suction side pressure,,go to my truck and when i return suction side is UP and at NORMAL pressure for conditions

System runs normal for balance of time I,m there
Question I,m leaning toward Indoor fan issue .WHY WOULD LOWSIDE PRSSURE COME UP SLOWELY?
I,m thinking the fan needs time to get up to adaquate Air flow
Its a older AMAna AIRHANDLER AND i DIDNT SESE THAT THE FAN HAD THE PROPER dELAYS -ON THE ON OFF CYCLE
 
Save
Like Like
#2 ·
First of all, you aren't really giving us any data to work with. Secondly, what is the metering device? Sometimes it takes a minute to build up some suction pressure, especially with an expansion valve.
 
#3 ·
Check indoor blower cap value and blower operation. Faulty stat energizing "G" intermittently? Loose wire, faulty relay? Proper airflow? Faulty TXV? Combination of things?
 
Save
Like Like
Discussion starter · #4 ·
ryan1088 said:
First of all, you aren't really giving us any data to work with. Secondly, what is the metering device? Sometimes it takes a minute to build up some suction pressure, especially with an expansion valve.
Click to expand...
Metering device not TXV
 
Save
Like Like
#6 ·
It's not uncommon for the suction pressure to take a few minutes to gradually rise until it gets stable even with everything working right. What was the line temp? If you let it run for a while and the SH was not too low then the chance of a refrigerant problem is much less likely. If you've got something going on intermittently it can be a bear to find sometimes. Another thing to look at along with the blower and cap is the blower relay and the outside contactor. I've changed many blower TD relays on a guess on a freeze up that I couldn't find any problems with that solved the problem. An intermittent sticking contactor can cause the unit to freeze up too.
 
Save
Like Like
Discussion starter · #7 ·
SGTSBC said:
Did the customer replace the filter after it froze up and before you got there. I have had that happen before.
Click to expand...
the filter was alittle dirty so I changed it after starting up the unit
 
Save
Like Like
#8 ·
SGTSBC said:
Did the customer replace the filter after it froze up and before you got there. I have had that happen before.
Click to expand...
Don't you love that? Especially when they don't tell you about the packed solid filter they yanked. I think they run down and do it so they won't be embarrassed and I can't tell you how many times I have seen one by the garbage can. When I go out on an iced up call after it has thawed I tell them hey if you changed the filter and it was dirty, show it to me if it's around. It helps me out. If they don't come clean and all else looks ok I tell them it may be an erratic blower issue. Relay or motor or whatever. Had one that would come and go and I finally said to leave fan on constant and it turned out to be a bad relay in the board.
 
Discussion starter · #9 ·
garyed said:
It's not uncommon for the suction pressure to take a few minutes to gradually rise until it gets stable even with everything working right. What was the line temp? If you let it run for a while and the SH was not too low then the chance of a refrigerant problem is much less likely. If you've got something going on intermittently it can be a bear to find sometimes. Another thing to look at along with the blower and cap is the blower relay and the outside contactor. I've changed many blower TD relays on a guess on a freeze up that I couldn't find any problems with that solved the problem. An intermittent sticking contactor can cause the unit to freeze up too.
Click to expand...
Thank you Gary
I,m thinking along those lines due to the fact that the fan start sequance didnt seem like I expected it.
I normally expect the blower to start first then the condenser and for the fan to have a time delay on shut down.
this system seemed not to work as expected
I wil devote time to check those items and confirm their proper operation.
bill
 
Save
Like Like
#10 ·
epacertified said:
I would think by now that It would not be easy to confuse me but-----
Customer called husband up early leaving on a buisness trip
A/C not coolig - Suction line iced over!!!
Cant get there till noon so ---
Now when I get there system has had time to thaw

I start it up --Clean filter ---- fan running seems like good air flow
gauges show lower than normal suction side pressure,,go to my truck and when i return suction side is UP and at NORMAL pressure for conditions

System runs normal for balance of time I,m there
Question I,m leaning toward Indoor fan issue .WHY WOULD LOWSIDE PRSSURE COME UP SLOWELY?
I,m thinking the fan needs time to get up to adaquate Air flow
Its a older AMAna AIRHANDLER AND i DIDNT SESE THAT THE FAN HAD THE PROPER dELAYS -ON THE ON OFF CYCLE
Click to expand...
That's fairly common after icing up. The evaporator was probably oil logged.
 
#11 ·
SH, SC? some units bring condenser on before indoor fan witch causes a psi drop on start up, Ive seen them with such a long delay I kept tripping the LPS on a whirlpool system. airflow, metering problem or low on refrigerant will cause it to freeze..... with the limited info I would go intermitting airflow
 
Save
Like Like
#16 ·
epacertified said:
I would think by now that It would not be easy to confuse me but-----

.......I,m thinking the fan needs time to get up to adaquate Air flow
Its a older AMAna AIRHANDLER AND i DIDNT SESE THAT THE FAN HAD THE PROPER dELAYS -ON THE ON OFF CYCLE
Click to expand...
I'm a famous "old turd" polisher. Those old units usually do not provide fan/condensor delays during start and stop cycles. They just start. "Hello power company, would you please get ready to get ready...?"

Edit to add constructive advice - given little info such as motor amps, capacitor value, etc I'll hazard a guess - maybe the blower motor or capacitor is on it's way out.
 
Save
Like Like
#18 ·
Youngwiseman said:
hmm i would just leave toward inadequate airflow also
Click to expand...
Seen a lot of units that where frozen. And then when thawed the suction stayed low for a while until the oil moved out of the evap. Only thing that caused those evaps to freeze was the plugged air filter.
 
#19 ·
need your running amps buddy... a blower motor can come on, but after some time, can reach above its amp rating, then shut down on a thermal and ahem, screw everything up.. so many possibilities a very vague question... Its always the dirty filter at first thou isn't it..

:grin2:

Then I end up having to pull the 8ft latter out, and finding the bad blower motor...

might wanna actually put your amp probe on the motor man, and get some electrical reading...
 
1 - 20 of 32 Posts
You have insufficient privileges to reply here.
About this Discussion
31 Replies
16 Participants
Last post:
epacertified
HVAC-Talk: Heating, Air & Refrigeration Discussion
posts
5M
members
275K
Since
2000
The #1 HVACR Community
Full Forum Listing
Explore Our Forums
AOP Residential HVAC/Refrigeration(Beenthere Zone) General Discussion Tech to Tech Chat - Residential Controls Refrigeration & Ice Making