Anybody ever change a 04 Civic Expansion Valve?

[antonmnster]

I'm trying to help out a friend solve some a/c issues on his Civic. It's a pretty cool car, but I'm used to euro cars.

As the engine revs past 3000 rpm, the high side sails right past 300 psi and the low side drops down to 20-25 psi. On the highway, the compressor is switching off - probably the high pressure switch cutting in.

So, it seems to me like the system is overcharged, and maybe has a sticky expansion valve. I might try to remove some refrigerant, but it seems like the low side might end up at or below 0 psi, pointing again to the expansion valve.

When I initially checked the pressures, I didn't think much of the 250-300 high side pressure, since that's where my euro cars seem to be happy.

But what the heck, I'm just an amateur at this. Anyone have any insights?

It looks like the expansion valve can be accessed through the engine bay. Has anyone changed one on this generation of Civic?

 

[StevieC]

The valves don't usually cause problem I would be more likely to think it's overcharged. Let some gas out to equalize the pressure on the gauges and see if it's still cold.

 

[Chris142]

Honda expansion valves keep me in business! With the proper charge is the low side goes into a vacuum the valve is stuck shut. I have never seen a valve on a Honda stick open, always shut.

3000rpm is alot of RPM for a Ac system in a stationary car. Is the condensor fan working?

 

[StevieC]

Really I have never seen one go bad in a Honda and I have done lots of A/C work on Honda's on the side. Maybe they use different valves in Canada?

 

[antonmnster]

What kind of pressures should I be looking for @1500 rpm? Let's assume 80-85F.

I was testing at about 1500 rpm; the owner reported that when he's on the highway (4000+ rpm) the compressor is cycling with POOR cooling. In town he says it's cooling well. That part says to me "overcharged".

When I'd rev the engine from 1500 to about 3000, the high side would shoot up to 300 and the low side would fall to 25. Seemed a lot more dramatic than I'm used to.

 

[Chris142]

Book time is 1.5 hrs. I've never seen one under the hood. Always in the evap case under the dash.

 

[Chris142]

Originally Posted By: antonmnster
What kind of pressures should I be looking for @1500 rpm? Let's assume 80-85F.

2.0-2.5x ambientr temp. 2.5x85-212 psi. Of course a dirty condensor or a failing fan will have an effect on high and low side psi but in a perfect world you would want 212 @ 85 degrees. Figgure closer to 225 with the average condensor with a few bugs and dirt in the fins.

 

[JakeR22]

I was going to change mine out when my a/c comp. went bad. It looked like a bear to get to, and that the whole blower motor assembly would have to be removed to get to it. So I passed, worked fine with the old one.