Hi,

Here's the issue I'm facing at the moment:

My AC cools pretty good at night; you can feel cold and chilly air coming out the vents, condensation on the windscreens and all.. the good stuff!

However, during the day, I feel it just blows cool air, not cold or chilly. And when I get out of the car, my specs don't get all fogged up like they do at night. So I'm led to believe at night the cabin's kept nice and dry and chilled. While during the day, the AC's not sucking out all the humidity from the cabin, or lowering the cabin temperature as quickly as it should. Another odd observation: if I keep the blower at full, the cooling goes down a little. A medium or low blower fan speed blows out colder air.

Clearly, it isn't cooling at full capacity when the sun's up. Also I've detected a new sound coming out of the AC ever since I had the evaporator core replaced: a hissing sound that sometimes goes away, at times doesn't, when the AC turns on and the cooling process begins. This sound is not to be confused of course, with the sound of the blower blowing out air through the vents.

Now, is this a receiver drier issue, an expansion valve issue, or both?

If it helps, I've had her since late 2005, it hasn't been driven all that much. But aside from the evap. core, I've had the compressor contact clutch replaced, in addition to the compressor bearing and seal. The temperature around here is between 32 and 35 Degs C at the moment (daytime), humidity's pretty high.

I just want to do as much research as I possibly can before sending it in. These 3s dealerships have a way of ripping a fairly large hole in your pocket if you're not careful or come off as a noob!

 

Symptoms suggest that there is not quite enough refrigerant. A charging machine should be used to remove it all down to a vacuum (during this, the quantity that came out can be measured), then install the proper amount by weight. If it worked better right after the car was worked on and has been getting worse, there is probably a leak.

Another possibility is the expansion valve was not properly installed. If it's a 2000 or earlier model it has the old style valve with a sensor bulb that must be attached to a specific place on the evaporator line and insulated with foam tape. 2001 and later have a block type valve that bolts on as one piece-- considered idiot-proof until a better idiot is invented.

First make sure the compressor stays engaged all the time in the daytime. Compressor should not drop out until the air is good and cold. Put a thermometer in the vent it should be close to 40 degrees (F) which I think is about 5 degrees C.

 

*I have gotten her checked up at 2 different shops. Refrigerant level is right where it should be. There are no leaks whatsoever. And no, it did not work better right after it was worked on. Cooling is the same today as it was the day it was worked on.

**It's a 2005 model. I have a little concern regarding the evaporator core: the bad one (stock) that had been taken out had insulation on all four sides of the core. The replacement that he put in was insulated only on three sides. Is that normal, or is something aloof? About the expansion valve.. how can it just go out on me like that? Cooling was just brilliant before I had the evaporator core replaced. And the previous core had a leak, that's why I had to change it. Honda recommends that both the expansion valve and receiver dryer needs to be replaced. One tech told me the expansion valve and evap. core get replaced together. I don't understand why these two components need to be suddenly replaced. Especially since the AC was working great on the previous evap. core that had a leak. That too while it was low on refrigerant, I might add.

***Well, that's the thing.. the compressor does not stay engaged all the time during hot weather. The air doesn't even get completely cold, and the compressor cuts out. I don't hear the clicking, but I can feel it in the revs. Whereas, in the evening or at night, it stays engaged longer. And the cabin seems to get dry and chilly faster. In addition, I've noticed when I drive with the blower speed set to low, there's a hissing sound coming from the AC when the compressor kicks in.. and if the revs drop or inscrease, or if say, I press the clutch ... this hissing sound either goes down/up or cuts out completely. Don't hear it much when the blower's running on high. But odd that the air feels colder when the blower is at medium or low, and not as cool when it's at max.

The thermometer test, should it be done out of direct sunlight? Blower speed set to max? The compressor stays engaged longer when the car's not moving. In fact, I don't think it cuts out at all. And cuts out randomely when the car's moving. How long do I need to stick the thermo in the center vent before measuring the reading?

 

Also make sure that the heater water valve (on the engine side of the firewall) closes fully when the dash dial is set to full cold. If hot coolant continues to flow through the heater core, the heater and A/C will fight each other and the heater will win. Adjusting the cable is often necessary.

 

Thanks for chiming in!

If that were true, then the cooling wouldn't be ice cold at night, would it? The AC cooling is also on par as long as the car is under a shade or it's fairly cloudy. But when it's been parked under the sun for a while, and then I turn it on...it takes it's own sweet time to cool the cabin. I can feel cool air coming out the vents, but the cabin temp doesn't go down as quickly as it ought to.

I've found the culprit BTW. Took her to yet another car AC shop. This guy was the straight forward no BS type. Did just a brief check up. Said everything is absolutely fine, except for the evaporator core, which isn't performing it's function a 100%. He asked me if I had it replaced. He told me, since the one I had installed is a cheap chinese manufactured core, and not the genuine one outfitted in these Civics, it's not sucking heat and humidity from the cabin as quickly as it should.

This explains all of the symptoms I've been experiencing. He says this is expected, and nothing unusual. 15% less cooling isn't that big a deal, and he's advised me to leave everything as is.

Oh well, at least I now know I got a screwy job from the previous AC repair outlet.

 

Yes there are some lousy knockoff parts out there. But I thought you had the replacement done by a dealer? They should have used a genuine part.

 

The dealer was taking me for a ride - they asked $320 for a replacement evaporator.

This guy I had it checked up at recently said a genuine evaporator coil costs $120. The knock off that I got was $65! And at the time it was being installed, he said: "Oh no, don't you worry, it's going to work as good as the genuine part..."... *****!!

 

Intersting discovery:

Left the car parked in a shade, AC running, for about 5 mins. Got back inside, it's nice and cool. Car starts moving, compressor doesn't cycle on/off as much. Nice and chilly!

Scenario # 2: Car's parked in the heat for 20 - 30 mins. Starts moving, AC on full, compressor starts cycling, especially when accelerating and upshifting. As long as the speed is kept constant, cruising, or rpms kept fairly low, the compressor doesn't cycle on/off as much.

Thoughts? Adjustment of the compressor clutch needed to prevent it cycling on/off this much during the day?

 

BTW, is it really true knock off parts significantly affect the AC's cooling prowess? Particularly when we're talking about an essential such as the evaporator core?

 

Have you measured your vent air temperature yet?

Compressor should not cycle off until the vent temperature (not necessarily the car interior temperature) is fully cold. Cycling off while the evaporator is not fully cold is usually a high pressure issue, pressure naturally gets higher with hot exterior temperature. Excessive high side pressure means the system could be contaminated with air (failure to evacuate before charging), overcharged with refrigerant or oil, or the condenser fans are not both working.