Automotive Air Conditioning Information Forum (Archives)

bueller on Thu July 12, 2012 7:04 PM

Year: 1998
Make: Nissan
Model: Frontier
Engine Size: 2.4
Refrigerant Type: r134a
Ambient Temp: 112
Pressure Low: 30
Pressure High: 270
Country of Origin: United States

Just looking for other expert opinions on this. I've had it vacuumed and recharged to the correct charge. Sticker on hood says 1.43 lbs +or- 1.1 ozs. We put 1.5 lbs in. Everything on the truck is factory original with the only exception being the discharge line I replaced three years ago. Vent temps when driving are only dropping to 58°. Where should I start?

Edited: Thu July 12, 2012 at 7:04 PM by bueller

Cussboy on Thu July 12, 2012 9:36 PM

I also have a 1998 Frontier 4-cylinder, 5 speed, since 2004 when I bought it with 100K miles. It's ahd the best AC of any vehicle I've had, and I live in Arizona. Now it's at about 170K miles and has not yet had ANY AC service, ever.

Anyway, how long have you had this truck, like did it formerly work OK, or always like this? Was it like this before you replaced that line 3 years ago?

Your pressures look OK if read at about 1500 rpm. Have you tried bypassing the heater core or clamping off a heater hose? Maybe you're adding warm air in. Maybe the flap/door is stuck on outside air instead of recirculate. Is the larger line from the evaporator cold? Is air coming out the vents towards you, or down under the dash or up at the windhield?

Is the volume of air that comes out strong, or has this decreased over the years?

Have you ever replaced your fan clutch?

Is the AC clutch slipping? How's that AC belt, too?

Edited: Thu July 12, 2012 at 9:37 PM by Cussboy

bueller on Fri July 13, 2012 1:41 PM

I'm in AZ as well

I've had the truck since 2003 and it blew ice cold until the discharge line leaked and replaced. It has never blown as cold since then. Just to double check the charge a few days ago, we recovered what was in there and it was about a 1/4 lb low. We put it on the vacuum pump and it held fine and it was recharged to the 1.5 lbs that's in it now.

I have not tried clamping off the heater hoses yet, but had planned to. I can actually hear the door slam shut when I turn the knob to cold. Vents are pointed straight into the passenger dept.

Vents blow nice and strong. I just had to replace the switch a few weeks ago because high blow had burnt, so that's fixed.

Fan clutch was replaced one month ago.

A/C clutch is not slipping and the belts were replaced when I put the fan clutch on.

Cussboy on Fri July 13, 2012 2:29 PM

Is the return line from the evaporator cold when you run it?

Is the clutch engaging but slipping sometimes (from either too-loose belt or oil on the compressor clutch)?

when you replaced the discharge line a few years ago did you also replace the drier?

Cussboy on Fri July 13, 2012 2:37 PM

Is the return line from the evaporator cold when you run it?

Is the clutch engaging but slipping sometimes (from either too-loose belt or oil on the compressor clutch)?

When you replaced the discharge line a few years ago did you also replace the drier?

Is it running cooler after refrigerant level was corrected for being 1/4 pound low? That's a considerable amount to be low.

With our recent 110+F temperatures, and our humidity, that's a lot of heat load. Is your 58F reading after it's been sitting outside in the sun, or after it was covered? Remember, it has to cool the air of whatever temperature it enters the evaporator at.

Dougflas on Fri July 13, 2012 4:07 PM

I think it is working fine. It is 112*ambient. Try using simple green and water on your condenser in case there are passages blocked with dirt and insects.

bueller on Fri July 13, 2012 5:28 PM

Cussboy, the return line gets pretty cool but not what I would say cold.

Belts are tight and the clutch is free from oil or anything else that would cause it to slip

No I did not replace the drier. I was told to try replacing it to see what it does since it's an inexpensive part.

Temperature dropped 5° at the center vent when we recharged it, conditions being the same within a degree or two.

I took the 58° reading after it sat in the sun all day until about 1pm. I ran it at around 1500 rpm to get it as cold as it would get which was 62°. I then took it for a drive and got it to drop to 58°

Cussboy on Fri July 13, 2012 9:00 PM

It should come in at at least 45F, these are good systems.

I wonder if you're 6 oz. low on refrigerant, that return line should be cold.