Proper A/C Temperature

Just had the the A/C fixed, compressor, etc. replaced on my 2003 CR-V. Now I feel the temperature is not as cold as it should be. What would be the right temperature it throws out? Per the Haynes Repair Manual it says to measure at the center vent with an accurate thermometer. It then says a fully charged system should cool down to about 40 degrees. It goes on to say that generally an A/C should put out air 30 to 40 degrees lower than the ambient temperature. Does that sound reasonable? I figure they are saying if the recirculate is of.

Using the above, I have a digital indoor/outdoor thermometer that I feel is accurate. I taped the sensor bud right over the center vent. I was only parked and the outside temp was 84, but I also had recirculate on. The lowest it pumped out after 10 minutes was 58. Using the statement above, the air should have been between 44 & 54. I intend to take more readings over the next few days with the recirculate on & off to get a better picture of overall performance.

My mind days there there should be some standard temperature range with the recirculate on so that outside air does not become a factor. Anyone have an idea of what would be proper?


It’s impossible to have an output temp that is not dependent on or affected by outside temperature. You’re not just trying to cool incoming air, the A/C system needs to “dump off” heat from the condenser, which if the finned part that’s in front of the radiator. If the condenser can’t cool the refrigerant enough you’re not going to get cool air in the car. Obviously the condenser can exchange heat more easily when it’s 70* than when it’s 100*. Humidity also plays a large factor in cooling efficiency and feel.

A 35 degree drop from ambient temp is acceptable in most cases, but that’s a rule of thumb. The other morning I was working on A/C and the temp in the shop was 58*. I wasn’t expecting a dash temp of 23*.

However, on a properly working system a 84 ambient I’d expect dash temp to be below 50 after 10 minutes. Your system could be slightly undercharged, slightly overcharged, excessive oil in the system, you could have a bad expansion valve caused by compressor failure, condenser fans could be weak, and a few other things as well.

Does the system cool better while driving?

38 to 40 degrees. Be sure that the hot water valve in the heater line is fully closed. The design that Honda uses often results with the valve not being fully closed even when the temp selector is fully CCW. It can make a 20 degree difference.

Just my 2 cents, but a 30-40 degree drop over ambient temperature kind of sucks and here in OK that would not work well on a normal for the summer 100 degree plus day.
At speed with the A/C on I’d be looking for high 30s to 40 on the outlet temperature.

It’s impossible to say what’s going on with the car without knowing what the pressures are at elevated RPMs and while it’s not often done, A/C system pressures should be noted on a copy of the repair order.
Usually the low side pressure is equivalent to the evaporator temperature so 58 degree outlet air would translate to around 58 PSI on the low side and that’s not good.

Any info in a Chiltons or Haynes manual should be taken with a grain of salt as both have a numer of inaccuracies and not just regarding A/C systems.
One of the Chiltons manuals I have for late model Chevrolets states that the radiator cooling fan should cycle on at 243 degrees as an example. Not by any stretch of the imagination.

Check the outlet temperature after driving 10 minutes at 45+ mph.

Thanks for all the input. I have connected the thermometer and drove around today. The high was about 74 and the temperature out of the vent got as low as 44, but typically bounced between 46 - 49. I need to get a few warmer days to do some real testing. So far tough, it appears a little better than I thought it was…

High 40s air on a 74 degree day is pretty poor operation.

Those numbers are SAD. I would expect a good shop to jump quickly to straighten out the problem when it occurs immediately after a major repair.

What would be even sadder is to discover that the reason for the compressor replacement was an “insufficient cooling” complaint and the cause is really an iffy blend door.

When the ambient temperature hits a 100 the occupants will be sweating as it is.

Sadly, @ok4450, there’s a better than even chance that is what has happened.

On a Honda, I can almost guarantee that the cable that goes from the dash to the blend door and then on to the hot water control valve is out of adjustment. It really is a bad design and I don’t think they have fixed the design yet, but I haven’t seen the newest models.

On our 97 Accord, when I manually close the blend door and the hot water valve, I get 38°F out the vents on a 90°F+ day. If someone adjusts the temp control and i don’t reset it, as often happens in the Spring and Fall, I get 60°F on a 80°F day.

Just last week I had an Accord in for poor A/C operation. Fixed the cable/valve and replaced the broken temp control knob. Got the A/C to 42* idling in the shop and never even hooked up the gauges.

Lets hope the OP actually has an A/C problem.

asemaster, could Honda have made that cable any harder to get to to adjust?

Oh, I don’t know. If it were too easy people would fix it at home and I wouldn’t make money doing it for them. I suppose if they had used an electrically operated valve we’d be complaining about using electronics where a simple cable will do. For as many Hondas are out there I don’t think there are an abnormal number of cable issues. It’s just that there are a lot of those cars out there.

Besides myself, I know quite a few Honda owners and most of us have or have had a problem with this cable. The newer Honda’s with climate control are even worse because you can’t just manually close the hot water valve, the automatic system will open it for you almost right away for some reason, then it can’t get it closed again.

I have installed manual water shut offs on many cars to totally stop the heater from getting hot because the factory system was expensive to replace and unreliable.

Well, the last two days have yielded different results. Yesterday with the temp in the high 70’s & lots of driving, it would get as low as 40, but typically stayed around 41-44. Today with a high of 88 it pretty much was 47 - 52. This was mainly city driving. At one pint it it crept up to 61 and stayed there for about 3 minutes, then slowly dropped to about 50. Tomorrow I wil be on the Interstate for about an hour & the high is supposed to hit 87, so I’ll see what that does. Eitherw ay, I feel I need to take it back for a check.

You might ask what both high and low side gauge pressures are at elevated RPMs. Generally speaking, you need in the 30s on the low side and 225-250 on the high side.

If it’s humid where you live you might also look underneath the passenger side of the car approximately where someone’s feet would rest and note if there is a condensation drip.
A system working properly in humid conditions should have a pretty steady drip with the A/C on.
Granted, that’s kind of a backyard method of determining things but…

I believe this is pretty much resolved now. I looked at the cabin filters. They were fairly dirty and had a lot of these seed kinda things that fall all over my driveway from a tree. I put new ones in. I took a ride for about 75 minutes on the Interstate, 86 degrees & 60% humidity. The air stayed between 40 & 42 the whole trip. As I turned it down when the cabin was cooled, that seemed fine. I did notice that in similar weather the next day that city driving (30 -40 mph) takes longer to get the temp to drop and then it typically goes between 42 - 47. However, it does seem to be cooling the cabin properly and I feel it is operating better than the old one did.

Thanks for all the help & info, I learned a lot from everyone here.