Checking for condesner coil operation.. How to??

[skidoox800]

Hey all,

Ive been a service tech for about 1 1/2 years now and I'm stating to do alot more commercial work. My question is sometimes I run into calls like customer says isn't keeping up all the time etc.

Say its a Cap tube system, how do I check for sub cooling if it doesn't have a service port on the liquid line? Can I put a pipe clamp on the hot vapor line leaving compressor atleast 8 inches away to stay away from excess compressor heat and pipe clamp after condenser coil and see drop across?
What is average drop if you can do that? If its a triple rolled or double rolled hard to tell if its moving enough heat out. How do you check that? Is there another way to make sure condenser is moving heat out like it should? Besides looking at pressures...

One more question how do you know what pressures should be besides checking subcooling/superheat?

[chucknorris]

liquid pressure = discharge pressure on most small systems.

Check charge by superheat for (most)cap tube systems.
Check charge by subcooling for (most)txv systems.

Liquid temperature is checked at outlet of condensing coil for subcooling measurement.

Allow system to run for 15 minutes before making any assumptions.

Typical AC or HP systems you should see a 100# difference in suction to discharge.

[chill out hvac]

check delta-t across condenser coil.

[2sac]

All condenser coils are dirty. Clean them.

[lisxs042]

How' often do they do tune up/ clean up. Check evaporator

[ar_hvac_man]

All condenser coils are dirty. Clean them.

yep, even if they look like they dont need it

[jpsmith1cm]

All condenser coils are dirty. Clean them.

Paying particular attention to the ones that need to be split apart to clean.

If you don't they aren't clean.

[hands]

If the unit doesn't have a liquid line access valve to get the sub cooling, you can measure the discharge superheat. Take the discharge pressure, convert it to temperature, take the discharge line temperature within 6" of the compressor and do the math.

[Bklyntek]

Hi Skidoox, I would Check ambient temp. at intake of cond.
& check disch. Air leaving condenser. Should be 20'-30'
Differance. Then check temp. Of liquid line leaving condenser,
Now convert discharge pressure to temp.(saturated cond.
Temp.) this will be your subcooling. I personally like to see
A balance of 10-15'. Hope this helps out.