Author Topic: Coil is freezing on old part of AC unit  (Read 3656 times)

Offline stumom

  • ***
  • Posts: 1
Coil is freezing on old part of AC unit
« on: June 14, 2012, 10:33:13 PM »
This time last year we had our outside AC unit replaced due to a leak, according to the repair person.  Our old Trane was replaced with a Lennox.  This week the old part of the AC, in the house, will work for a little while each time we start it and then the air flow reduces and becomes warm.  We called a repairman who said it was probably because the outside unit is new and the inside unit is 17 years older and they work under different types of pressure and coolant.  He suspects our coil inside is freezing up.  The repairman that replaced the outside unit last year said that's not possible.  We're not sure who to trust.  The old repairman from last year said it's probably because the inside coil is dirty, which has not been investigated yet.  Any advice?

Offline Admin

  • Administrator
  • *****
  • Posts: 2364
    • HVAC TECH GROUP
Re: Coil is freezing on old part of AC unit
« Reply #1 on: June 15, 2012, 06:11:19 PM »
If you look at the outside unit find the rating plate and post the model number here.

Has this new AC ever worked before the icing up started?  If so it's unlikely they installed an outdoor unit rated for R410a refrigerant, which would be incompatible with your indoor coil rated for R22 refrigerant.

Hopefully it is just a dirty coil because if it has developed a leak a new indoor coil could cost up to $1500 to replace.

It shouldn't take a tech long to diagnose the problem and determine if you have lost refrigerant or have an airflow problem.  At this point it's hard to say if the indoor coil started leaking after the outdoor unit was replaced or if it was leaking the whole time.

Offline rmuntz

  • Pro Techâ„¢
  • *****
  • Posts: 111
Re: Coil is freezing on old part of AC unit
« Reply #2 on: June 16, 2012, 08:45:10 AM »
This time last year we had our outside AC unit replaced due to a leak, according to the repair person.  Our old Trane was replaced with a Lennox.  This week the old part of the AC, in the house, will work for a little while each time we start it and then the air flow reduces and becomes warm.  We called a repairman who said it was probably because the outside unit is new and the inside unit is 17 years older and they work under different types of pressure and coolant.  He suspects our coil inside is freezing up.  The repairman that replaced the outside unit last year said that's not possible.  We're not sure who to trust.  The old repairman from last year said it's probably because the inside coil is dirty, which has not been investigated yet.  Any advice?
Sounds like too many "probablys". If you paid these repairmen to come out, they should come up with a better diagnosis than that. Generally, in todays world, if you need to replace either the inside or outside unit, we try to replace both to prevent issues down the road. There are ways to do the inside or outside separately and replacement equipment is available to do it correctly, but for what you save for only doing half it's not really worth it. Like admin said, if the a/c worked after the initial repair, then there is probably another issue.