Air conditioner vent temp?

[KsRancher]

I was wondering what is a reasonable expectation for the vent temperature of a home air conditioner?

Unit was new in 2017. Don't remember the efficiency of the unit. But it's one with the pvc vent pipes. We keep our thermostat set at 73°. The vent closest to the unit blows air 58°-60°. Thermostat is right by the return air. So I am assuming the air going into the unit is 73°.

Reading online most things say 20° is an acceptable temperature drop. I am getting 13-15°. I have taken the top off of the outside unit and washed it from the inside out until it was super clean. That didn't change anything. Change air filter regularly. The unit seems to be running WAY more than my wife or I remember it running since it was new. Yes, it's HOT here. But it has been this hit before here.

Just wondering if I am expecting too much out of my AC or if there is an issue

 

[Dos Perros]

Do you have an HVAC tech show up once a year to check it out? Ours always notes how many degrees of superheat our unit has. Maybe it's another metric...but they're essentially noting performance on the refrigerant cycle and they can pull up history and check it against when it was new.

 

[GSPHUNTER]

Air coming out of supply air should be 20 regs. below room temp. If room is 76, then supply air should be around 56 deg. plus or minus a couple degrees. If air is too cold, say 40 degrees that means evaporated coil in around 25 regs. and will start to freeze up resting air flow, and causing potential problems with compressor.

 

[Jstumbaugh]

An R410-A system will be about a 12 deg delta at the evaporator.

 

[ODB]

I get 19 degree difference between the air just at the filter and the air at the closest vent. I JUST went through getting a new system installed. Frankly, the new Freon does not seem to work quite as well as the old r22 but it is in spec.

On install, the difference was only 15 degrees and I was pissed, the house would not stay cool. Turned out the knucklehead installers did not set the CFM correctly and the there was too much volume. Another tech turned the volume down and the differential went up.

Try to check the air right at the filter over the unit versus relying on your thermostat - provided you have a downdraft unit. We have west-facing bonus over garage and it is a heat factory. On days over 95-97 we use a small window unit to cool the air since that will all go into the return. If we do not cool that room it will get 94 degrees.

And PVC exhaust means 95% efficient.

 

[GSPHUNTER]

I get 19 degree difference between the air just at the filter and the air at the closest vent. I JUST went through getting a new system installed. Frankly, the new Freon does not seem to work quite as well as the old r22 but it is in spec.

On install, the difference was only 15 degrees and I was pissed, the house would not stay cool. Turned out the knucklehead installers did not set the CFM correctly and the there was too much volume. Another tech turned the volume down and the differential went up.

Try to check the air right at the filter over the unit versus relying on your thermostat - provided you have a downdraft unit. We have west-facing bonus over garage and it is a heat factory. On days over 95-97 we use a small window unit to cool the air since that will all go into the return. If we do not cool that room it will get 94 degrees.

And PVC exhaust means 95% efficient.

Yup, proper CFM is very important for best results.

 

[Wolverine]

The PVC vent has zero to do with the A/C efficiency rating.....it only represents the efficiency of the furnace be over a 90%. The A/C is probably somewhere between a 13 to 16 seer raiting 16 being the higher efficiency rating. Generally speaking you should have a temp split of 18-20 degrees +/- a couple degrees for A/C. Need to have the HVAC tech check to make sure your system has the correct amount of subcooling or superheat depending on if you system is using a piston or TXV. That will insure that the system has the correct amount of refrigerate in it. If it's not charged correctly nothing else matters. Blower speed can help adjust the temp split but it all starts with the unit being charged correctly.

 

[GSPHUNTER]

In forty years of working A/C and refrigeration one thing I heard is, a little knowledge is a terrible thing. I followed up on guys who installed the system, ran and hooked the copper lines between the condensing unit and fan coil and didn't evacuate the line set and evap. coil before they opened the valves on the condensing unit, if the unit came with partial charge. Then never topped off refrigerant charge. Not that it really mattered at that point because they never ran a vacuum pump on the system.

 

[Wolverine]

In forty years of working A/C and refrigeration one thing I heard is, a little knowledge is a terrible thing. I followed up on guys who installed the system, ran and hooked the copper lines between the condensing unit and fan coil and didn't evacuate the line set and evap. coil before they opened the valves on the condensing unit, if the unit came with partial charge. Then never topped off refrigerant charge. Not that it really mattered at that point because they never ran a vacuum pump on the system.

This is why I love the "diy" guys.....they end up sending a lot of business our way. Installing hvac equipment is fairly easy. Installing it correctly and setting it up properly is a different story especially the a/c side. Still not rocket science but wrong gas pressures and your furnace soots up or worse. Wrong fan settings and you over or under heat of freeze up, and as you mentioned lack of running the vac pump which is probably the most important part of the a/c install.

 

[KsRancher]

Do you have an HVAC tech show up once a year to check it out? Ours always notes how many degrees of superheat our unit has. Maybe it's another metric...but they're essentially noting performance on the refrigerant cycle and they can pull up history and check it against when it was new.

I don't. So I don't know if it's normal or if there is an issue

 

[Stalker69]

Like most others have said, delta t should be around 20 degrees. If it was not evacuated ( down to 500 microns) you will have issues. Or if unit is not charged correctly, or has a small leak ( losing refrigerant) are very common reasons. Let us know what you find out ?
Do you have access to a refrigeration manifold ?