1986 Accord AC Question

I have the carb model 5 speed. The AC light comes on in the dash, but the compressor doesn't turn on. I traced wires and when I checked for power to
the compressor, it ran when the test light probe touched the wire. It also works by direct power to it. I assume there are relays for it. I also noticed a switch on the line, assuming it's for low coolant pressure. My question is, will low coolant prevent the compressor from activating? I need to switch it over to 134, but don't want to waste time and coolant until I trace the problem down. My repair manual doesn't mention anything about this other than taking it to a qualified technician...
Thanks for your help.
John
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Ah, I love those cop-outs in the manuals. The funny thing is that there is often some troubleshooting you can do yourself.
I'd definitely check out the low pressure cutout switch. Usually you will get a long period of excessive compressor cycling before it refuses to work at all, but a large leak or a long time without using the A/C can skip you past that. Anyway, pull the connector off the switch (with the engine off) and measure the switch. It should have continuity. Alternatively, you can put a jumper in the connector to see if the compressor pulls in (engine and A/C on), but don't do that for more than a moment to avoid damage to the compressor... or replace the compressor connection with your test light.
I am ambivalent about R-134a conversions. R-12 is outrageously expensive these days, but converted systems just don't work as well as unconverted systems of either type.
Either way, if the pressure switch is what is holding the compressor off you will need to go to a pro - either to get the R-12 charge (you can't buy the stuff) or for a proper conversion. If it's not the problem, come on back and we can go deeper.
Mike
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
A relay can still show voltage when energized but not conduct sufficient voltage to operate an actuator or motor, solenoid, etc. FWIW
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I found and jumped the low pressure switch and it seemed to work. I did the 134 conversion myself with new o-rings, oil, and the refrigerant. Cooled to 48 degrees. It could probably take another small can, but it's working. At least for now. Leaks may show in a day or so...

Thanks for the help.
John
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.