I live in Arizona, (Phoenix) and my heater has been blowing all night long with the thermostat set to 78 degrees and the temp. in the house at 76 degrees.

I have a heat pump unit and was wondering what the common problems of "not blowing warm air" are when the heat is on.

With a heat pump it could be one of many possibilities. Do you have any auxilliary back up heat ? (electric strip heaters) I'm not sure what the outdoor temp is in AZ but it ought to be warm enough outside to still run on the heat pump alone. Here in Ohio once outdoor air temp is below 20 or so heat pumps don't do much, and strip heaters are needed for back-up heat, or when defrosting the outdoor unit.        

If you still are trying to run off of the heat pump (compressor) is your outdoor unit running at all??
It could be low or out of refrigerant.   Is there ice/frost on your outdoor unit?

Did it work fine and then just stop heating ?? It could be a reversing valve or relay or even possibly stuck in the defrost mode with a bad sensor or circuit board.

Unfortunately heat pumps aren't that easy to diagnose online and good heat pump techs are tough to find.... around here in Ohio anyway.  If your outdoor unit is running (fan and compressor) you will probably need to pay someone to come out and put a set of gauges on it to see what is going on for sure in the system.   It's not much infor but I hope it helps.  IM me here or e-mail me if I can help.

appreciate the response.

no aux. heaters.

We had a freeze warning with temps in my area down to 32 degrees night before last.   That's when we noticed the unit ran all night and wasn't putting out warm air.  

Last night was cold but not as cold as the night before.   We still had the same problem.

We have a tech out looking at it now but I wanted to consult the experts here and compare it with what the on-site guy says.

Let's hear what his final "diagnosis" is when he's done..... and whether or not it really fixes it.

TAG

<---- I eat heat pumps for breakfast.

ETA - JETWC has asked all the right questions.

Facts:

3.5 ton system.
10.5 years old.
harsh summers

From the invoice:

"Found compressor internally by-passing at 190 to 200 psi.  Checked freon--ok.  The compressor will still operate but be less efficent.  At a minimum I would replace the compressor.   Also for better air flow I would recommend adding another return in the living area and the bedroom."

He was also recommending a 4 ton unit considering the sq. footage of the house (1650) and the smaller current unit (3.5 ton).  

He says that he can hear freon "hissing" as it by-passes inside the compressor.

This outfit was the only one to "Pass" a hidden camera sting on un-ethical AC service companies done by a local TV station.

New compressor== $1200 +/-

New 4 ton unit== $4 to 5K +/- (don't think so)

Adding a return==$800 to 1K +/- (don't think so)

His prices on the condensing units are high. Get a few more quotes. Not a bad idea to replace the condensing unit rather than the compressor as the new units use alot less electricty. Look for a unit with a SCROLL compressor.

1st question 78 degees? why so warm?
Second A 5k strip heater connected to a outside "stat" would only add about $150 to the insallation cost.
If you ahd the local newsdogs use your system for a report I am sure that there are many companies willing to "fix" your problem. Knowing that the fix will be replied in the local media.  That is free , or at a low cost for the media coverage

Don't buy anything from any contractor that won't at the very least do a manual J load calculation. Old school goes by square footage, more or less hit and miss.  I'm an A/C contractor in Houston TX.   Replace the condensing unit and not the compressor as someone else said.   It's possible that the air handeler and refrigerant piping would have to be replaced in order to get the full SEER
rating.   It sounds like your unit, possibly a 10 seer, and being wore out, possibly an 8 seer.  By the end of the month, manufacturers can only produce 13 seer, it's a federal mandate.  However, they can sell the remaining 10 and 12 seer units until their supply is depleted.  What brand of equipment did he propose to replace it with?  That has alot to do with pricing.   You're looking for the quality of the install, not just the brand name.  Try going to hvac-talk.com but don't ask for pricing because they'll nuke the question.  Feel free to ask any question you want except pricing.  Good luck!

This wasn't a company with the initials AHM is it?