# HVAC Cold Line from Compressor -- How Cold?



## jaythorpe522 (Sep 7, 2010)

How cold should the cold line be?

Or, what else can I do before calling a pro? I'm pretty handy and fairly unknowledgeable.

My utility room is pretty cold; my bedrooms are not.

My system is badly designed for the house -- the house is narrower in the back third, wider in the front 2/3. One duct comes off of the furnace/blower/call-it-what-you-will and serves the front half of the house. It is a bit leaky around the seams -- the ductwork is narrower than the (making up my terminology as I go) lead out from the blower, so the installer cut down some sheet metal, made a rough seal, gooped it up, taped it up, and tried to collect his check from the contractor who lost his shirt rehabbing the house right before the market crashed. A second duct, nearly as large, comes off the furnace/blower for the back 1/3rd of the house.

So I know I'm not starting from a good point as far as airflow, BUT, last summer it cooled the house pretty well. I left the back bedroom door open mostly, closed off the 1st floor front registers, and things balanced out well enough.

This summer, it just seems like we're not cooling down. I am going to start addressing some of the flow/leakage issues, but since nothing has changed since the mostly-functional situation last summer, I wonder if something's up with the cooling as well.

So, how cold should that cold line be, and what should the delta-temp from air into blower/air out of blower be for a well-functioning unit? And what should I do to it that doesn't need a pro (i.e., freon needs a pro, but, should I be able to clean out the compressor myself)?

Thanks much! Sorry for the trademarkedly-long post.

jw


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## SABL (Jul 4, 2008)

Hi JW,

How's the condition of the furnace filter?? Is it a pleated cartridge type or the cheap 1" 'replace every month' standard garbage?? 

Heat pump or AC only??

Has the system ever been balanced??


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## jaythorpe522 (Sep 7, 2010)

Cheapo, but I do replace it every month, and the same/similar cheapo brand since I bought the house 3+ years ago.

Heat pump, wasn't sorely needed this winter (warm winter, attached house), but last summer & winter before were put to good use & worked v.well.

Dunno what balancing is, but I doubt it. Contractor was racing to finish the place & get to market end 2007. When things went bust he stole his own lux appliances & defaulted; I wound up w/a great priced short sale with "features", especially in the finishing touches of the hvac (already listed, plus exhaust pipe directly over compressor, do-not-pass-go-do-not-collect-inspection-certificate), unlabeled circuit breaker box, Cat5e x2 & cable x2 to every room in the house, a nifty line distribution system, but nothing either terminated or labeled 

In other words, if it's testing or trouble shooting or refining, not done.

jw


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## SABL (Jul 4, 2008)

Sometimes those cheap filters don't catch everything and the A coil (inside the air handler or furnace....follow the cooling lines) may become dirty. Check the cooling lines going to the furnace....one will be hot and the other one cold. The cold one should feel as cold as a can of pop that you just pulled out of the fridge. If it is, check the filter and the A coil in the unit. 

Years ago I forgot to change my filter and didn't get enough air flow through the A coil....it iced up.....:sigh: Simple solution with a heat pump....turn the heat pump on and set the thermostat to heat. It'll de-ice the A coil in about 15-20 minutes. The first time it happened I used a hair dryer to thaw it out.....second time I was a little smarter and used the heat pump....:thumb: 

Balancing is done with the use of dampers installed in the ducts that go to the individual rooms....damp (restrict) the air flow to the rooms nearer to the furnace (air handler) and force more air to the rooms that are further away. If no dampers. you can use the air flow control on each register.....except when some people want to hog the cold air.....:laugh:

It wouldn't hurt to have a check-up on your heat pump. I didn't have mine checked and it only lasted 6 years....and it's a name brand unit. The original one lasted 15 years with no check up.....I was lucky.


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## jaythorpe522 (Sep 7, 2010)

I think the airflow between the filter & coil is the culprit -- v good suggestion, thank you! Cold line is definitely cold enough when running.

Can't figure out my way inside tho'! Can get to outside/top of A, but I assume the air comes up through it? It's not iced but tons of condensation.

Looks like to get in to clear the air path, I need to take off the sides of the furnace... but between the intake/exhaust pvc and ductwork on one side, and the gas line and water heater on the other side, I need a team of old-school chimneysweep boys to get in there... I'm 6' 220lb (183/100) and my left arm might fit back there, if I could wield it in my right hand... bummer.

Thanks for the info -- yeah, we do the individual register 'dampening'. I was thinking of lining the floor registers with foil to block them even more.

I think I'll treat the blower motor as best I can, clean the compressor best I can, and maybe blow some air backwards w/ a shopvac through the A, and then prob wind up calling a pro...tho' some of the neighbors' kids are skinny. Anyone know a flying nanny?

Thanks again!


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## SABL (Jul 4, 2008)

There should be sufficient access to remove one of the inspection covers. 

Make sure all air returns are clear and are not blocked by furniture.....that can happen. Air returns aren't the best looking thing in the house and are often concealed by furniture.....make sure the furniture is pulled a few inches away from the wall to allow air flow. The fabric on a couch/sofa can completely seal the return and cause loss of air flow.....beds pushed against a wall can really block air flow if the return is in that wall. Get the air moving before calling a pro.....but do have regular inspections made.


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