vegas4x4

Hello all,

I bought a 2000 Civic two years ago (from a friend, really as a favor) and the AC has never worked well in the summer heat of Las Vegas. It works OK when you're on the highway or moving in traffic (takes about 5-10 minutes to cool down), but if your idling or sitting in traffic it sucks.

Today for example it was 100 degrees out this afternoon. If I'm driving around and actively moving (after 10 minutes or so), the vent discharge will be about 60 degrees. As soon as I hit a light or idle it will raise up to about 70 degrees within 3-5 minutes.

70 degrees just doesn't cut it and it's only gonna get hotter!

If it's in the evening or cooler parts of the year, it works OK, it will get to a vent discharge temp of 52 degrees (that's when the AC thermostat cuts the compressor).

This is what I've done:
1) Connected a manifold to check pressures, they seem to be in spec with the pressure/temperature/humidity chart in the service manual. (I can provide specs if anyone is curious)

2) Recharged by weight (evac, vac pump, charge by weight) with approx 22oz of R134a.

3) Replaced the condenser fan (it was working, but definitely was weak), drier, and expansion valve.

4) Checked and made sure the compressor is engaged and not cycling off (watching the AC clutch bolts spin). I also jumpered the AC thermostat (in the evap) for testing purposes.

So basically I'm at my wits end. Do the Honda's just have weak AC? My ford truck is blowing 40-45 degrees within 5 minutes at idle.

Any suggestions? I'm about ready to replace the compressor (maybe it is weak?) or take it into a shop and pay someone to diagnose it out. The car has 135k miles on it.

Any advice would be greatly appreciated.

Former User

Post the refrigerant high and low side pressures with the engine idling at 1500 rpm. Also post the outside temp when the pressures were measured.

vegas4x4

I just took a measurement, this is evening though, it's working OK right now.

Ran it at 1500 rpm for 5 minutes (pressures are @ 1500rpm) with AC on max/recirculate.

97F outside temp
30 psi low side
250 psi high side
55 degree vent discharge temp

I'll get some numbers tomorrow afternoon when it's not working well and see what they look like.

ej#ALLDAY

Ford trucks have the worlds best a/c lol..coldest ive ever felt

strategy400

Did you pull a vacuum before weighing in the charge? How much did you weigh in? Did you add any oil (how much)?

Former User

At 97F and 30% humidity, the low side pressure should be about 44 PSI and the high side pressure should be about 400 PSI with the engine running at 1500 rpm.

The pressures suggest that the system may be low on refrigerant, even though the vent discharge temp is fine.


But given that you just charged the system with the proper weight of R134a, then here's what to consider:

SOL619

Have Hondoctors take a look at it if you ever find yourself "beat" on the situation.

vegas4x4

I wasn't sure about reading the chart since we're at 12% humidity here (according to my weather station).

I'll check the numbers tomorrow afternoon and post. I may have to recharge, I noticed it looks like there is a small leak at the low side schrader valve :/.

Thanks for the info in the right direction!

I did pull a vac prior to charging. I added 10ml of oil to the dryer, which is what the service manual specs. I added it directly to the dryer rather than thru an oil injector at the service port. Hopefully that was right!

vegas4x4

Just thought I'd post an update.

I checked the pressures again and they did seem a little low, again. I also noticed I can hear a "gas expanding" type sound in the evap when it's low on refrigerant.

Anyways, I had it evac'd, vacuumed it down, and charged it with 23oz of r134a. I tested the pressures the next day and they were:

85F @ 20% humidity
55 discharge temp after 10 min @ 1500rpm
240 psi high
30 psi low

It's been a lot cooler lately, so we'll see how it is when it gets really hot out. For now it definitely seems to be cooling better. Still takes awhile to cool down initially, but I do notice the temperature doesn't creep up anymore when you're idling at a light once it's cool inside.

I also noticed the "gas expanding" sound under the dash has gone away.

Thanks for the help. I'll keep posted if it returns.

vegas4x4

Well, I'm back.

It's hot as heck here again and the AC isn't pulling its weight. I recharged it last weekend with 23oz r134a.

I just put gauges on it this afternoon and this is what I got:

Ran @ 1500rpm for 10 minutes.
95F ambient air temp @ 12% humidity
120F intake air temp (tested at the passenger floorboard) @ 12% humidity
Low side - 50 psi
High side - fluttering between 420 and 460 psi. (I checked, the pressure switch wasn't kicking the compressor off here, I assume because it was fluttering. If I revved it up further the pressure switch would kick off the compressor).
Outlet temp - 81F

Not sure if the fluttering is expected or possibly indicative of a bad compressor?

Any ideas?

Former User

Both pressures seem too high.

Does the condenser fan always run when the compressor clutch is engaged?

Is the condenser clogged with bugs/debris or are the fins bent, preventing proper air flow?