AC expansion valve

Hah!  I just happened to have two long M5 screws in stainless steel!    I had to drill that rotted steel bolt almost from end-to-end.   Then I had to epoxy the plastic tube clamp back together after I got a little over exuberant with the hammer and punch.   But it’s all back together and cooling!   Another nasty job that shouldn’t have been that difficult.

Removing the evaporator is a pretty straight forward job on the spyder.  I’ve never removed one before in any car.  If it wasn’t for that rusty bolt...

What were your pressures doing when it acted up? Just curious because I’ve never seen an intermittent expansion valve but if it was causing a extremely high or low pressure maybe it was causing the compressor to shut off.

I was too lazy to check pressures while it was doing it’s “I’m not blowing cold” thing.  It would just cycle warm for no reason, yet the compressor was still turning.   Cycling the AC switch from 5-20 seconds would “reset” it so it blew cold again. 

There also is a temp sensor on the coil face..  it detects too cold of a surface, and will turn off the compressor to allow defrost..  feeds to the Dash Cluster then back to the Engine ECU for Compressor/AC Control..

Cap

Posted by: Cap

There also is a temp sensor on the coil face..  it detects too cold of a surface, and will turn off the compressor to allow defrost..  feeds to the Dash Cluster then back to the Engine ECU for Compressor/AC Control..

 

Cap

I think that’s the thermistor (thermocouple) that hangs on a stalk inside the evaporator box.   I replaced it - with great expectations.   But no joy.  

And glad to see you back Cap!  

I THOUGHT I had fixed the problem.   The AC blew cold all the way home in 100F heat.   But then...I hooked up the gauges in the garage and caught it going stupid.   It quit cooling, the compressor kept pumping, the low side jumped up to 125psi, and the high side dropped to 200psi.    (Pressures while it was cooling properly a few minutes earlier were 55psi low, and 320 high - with 110F intake air temp).

During a second 60 minute drive this evening it again did very well, and only went stupid one time.   I waited patiently for it to "thaw" or "unstick" but it never did.  SO, I cycled the AC switch off for 5 seconds.  Then back on.  Viola - the system started cooling immediately, and continued to cool the rest of the way home.  WTF?

When the system goes stupid - the compressor is still turning!

The system now has a new expansion valve, and new thermistor.  All that's left is the stinking compressor.   Is there some kind of bypass valve in the compressor?   When the expansion valve clamps shut, I presume something in the system will bypass the dead-head fluid, since the compressor keeps pumping wide open.

I'm open to ideas.

New theory!   A hotrodder in my office said his GM compressor will start rattling, and his AC will quit cooling.  And it’s intermittent.   The theory is that reed valves in the compressor are sticking open, temporarily.   Which would make sense that they might “reset” and snap shut when I turn off the compressor for 5 seconds.