paul_h
22-07-2007, 09:37 AM
Hi, I've got a problem with an old cabinet, it's really old and about 300L capacity.
The condenser fan motor bearings keep seizing up annually.
It's an old r12 unit on r134a, done before I worked there. The condenser is bottom mount under the cabinet, it has no fan cowling and air off it pretty much goes outwards from the fan, instead of flowing backwards and out the vents.
There was a lot of hot air being recycled because of this and it's mounting under the cabinet. So I packed up the gaps beteen the cabinet and condenser so less air was being recycled.
The only problem is the high air of from the condenser, it's about 55C, while the unit in it a 20C air conditioned space.
The fan motor gets no benefit of airflow due to the air being pulled off the fan to the sides because of lack of cowling and fan design, so the fan case is constant 50C+.
Now to me, that's probably causing the fan motor bearing failures every year.
But I'm not sure if it's just an airflow propblem or it may be a refrigerant problem causing exceess condensing temperatures.
Problems:
1) This customer can't spend money replacing equipment, the business owners (500km away) won't authorise it. But they do need everything working so he can give us money for repairs. It's taken us two years to convince them to upgrade their main a/c (looking at a 50k job here, so I don't want to piss him off either.
2) this is a really old cabinet, if it worked for 30 years on r12 without a cowling around the fan, I can't say it needs one to work.
3) I can't say just to get it reclaimed and recharged on a whim without having definite answers why, this guy spots bull**** a mile away. He's been managing hotels and shops for a while, he knows what he's got to work with is ****, but he doesn't have much say in it either. He's gone through a lot of refrig companies to find us, and he's staying with us because he thinks I know what I'm doing :).
So any ideas what to look for, as cabinet temps and all pressures look OK except for the cond temp. The fan is going the right way, condenser is clean etc.
The condenser fan motor bearings keep seizing up annually.
It's an old r12 unit on r134a, done before I worked there. The condenser is bottom mount under the cabinet, it has no fan cowling and air off it pretty much goes outwards from the fan, instead of flowing backwards and out the vents.
There was a lot of hot air being recycled because of this and it's mounting under the cabinet. So I packed up the gaps beteen the cabinet and condenser so less air was being recycled.
The only problem is the high air of from the condenser, it's about 55C, while the unit in it a 20C air conditioned space.
The fan motor gets no benefit of airflow due to the air being pulled off the fan to the sides because of lack of cowling and fan design, so the fan case is constant 50C+.
Now to me, that's probably causing the fan motor bearing failures every year.
But I'm not sure if it's just an airflow propblem or it may be a refrigerant problem causing exceess condensing temperatures.
Problems:
1) This customer can't spend money replacing equipment, the business owners (500km away) won't authorise it. But they do need everything working so he can give us money for repairs. It's taken us two years to convince them to upgrade their main a/c (looking at a 50k job here, so I don't want to piss him off either.
2) this is a really old cabinet, if it worked for 30 years on r12 without a cowling around the fan, I can't say it needs one to work.
3) I can't say just to get it reclaimed and recharged on a whim without having definite answers why, this guy spots bull**** a mile away. He's been managing hotels and shops for a while, he knows what he's got to work with is ****, but he doesn't have much say in it either. He's gone through a lot of refrig companies to find us, and he's staying with us because he thinks I know what I'm doing :).
So any ideas what to look for, as cabinet temps and all pressures look OK except for the cond temp. The fan is going the right way, condenser is clean etc.