8/19/09 12:13 a.m.


I recently had an AC meltdown in my Honda CRV. The compressor and expansion valve were replaced, the system flushed and recharged for 15% the value of the whole car.

After that it felt more like a swamp cooler than refrigeration. When the AC clutch was engaged the engine drag was excessive and the compressor was noisy, and it cycled every few secs. I took it back, and they replaced the compressor again.

Then it was a little quieter, but the drag was the same and it was still not as cool as originally. At 3k RPM in 5th gear, it would cycle on for 7 sec and off for 3, constantly. After a couple of days of this, I ran it to 5k in 3rd for a couple of minutes. It cycled on for 1 sec and off for 4 then on for 4 sec and off for 4, at which point the pattern would repeat. But curiously on returning to original road speed, the cycling stopped and the drag seemed less. Cooling improved too but not right. Now cycling starts at about 3600 rpm.

So I'm thinking "what if" a piece of that aluminum shrapnel found its way to the expansion valve and partly clogs the orifice. Could the engine load and cycling arise from excessive restriction in this closed loop system? Could my brief engine revving shift this fleck to reduce the occlusion and improve things?

So I present my vehicle and my hypothesis to the auto shop and they grumble about not only was the original reman compressor bad, but the expansion valve too. They sort of blew me off, but schedule me to replace that part next week, because the Hi pressure side was fluctuating (seemed 230-300 at about 1500 rpm).

Any ideas from you guys who deal with this stuff daily?

ignorant SuperDork
8/19/09 4:18 a.m.

short cycling compressor? Maybe they undercharged or overcharged the thing.

4cylndrfury Dork
8/19/09 6:40 a.m.

Lol...and here I thought this would be a thread about using a cooltec shirt on a bicycle

as far as your problem, my guess is its overcharged - Think of the cycle as a wave on an oscilloscope The peak and trough of the wave are the on/off of the cycle. The expansion valve cycles faster BC high pressure causes the normal peak and trough of the cycle to compress. Was a pretty common complaint after you did your first AC recharge job if youre the new guy at jiffyvalvolube.

Jensenman SuperDork
8/19/09 6:42 a.m.

I vote a restriction in the system, as you suspect. You mention compressor and expansion valve, did they replace the receiver drier as well? If that's clogged with shrapnel, that could be the problem. Whenever I sold an A/C compressor, the techs would flush the liquid lines and replace the receiver drier.

TJ HalfDork
8/19/09 8:46 a.m.
4cylndrfury wrote: Lol...and here I thought this would be a thread about using a cooltec shirt on a bicycle

Me too, my answer was to pedal faster or go out earlier in the day before it gets too hot.

44Dwarf Reader
8/19/09 8:46 a.m.

Could also be a miss adjusted clutch. there normaly shim washers behind the coil, or at least there is on ford trucks.

Buy a set of HF gauges and find out.

Grassroots Motorsports Magazine

Subscribe Today

Also get your instant access to the digital edition of Grassroots Motorsports Magazine!

Learn More