Engine runs rough when ac is running
 

I have an 89 s10 blazer 2wd 4.3 and I recently filled ac with new coolant. Been noticing truck runs real rough when driving and sitting at a light. I recently went thru and gave her a lube and tune up. And this time of yr in my area is dry and hot and wife was asking for ac. So I went and got a can of 134 coolant with gauge had some difficulty adding it being my first time doing it. But eventually figured it out and had to go get a second can to top off. Still not alot of cold air and motor runs rough. Anyone have any input on this? I'm wondering if I should put a timing light on motor to see if it may have advanced or retarded some how. I am a diyer person and have some backyard mechanic experience but never had much to do with AC. Any help is very appreciative. Hope all is well with you and yours during this covid stuff. Respect

P.s. motor ran rough with the first can also. I need to plug o2 sensor in but other than that have no idea why it's running rough.

The O2 sensor MUST be working. Never disconnect it. The plug on my S10 had a loose terminal, the fuel system went righ and destroyed O2 the sensor- it got carboned up.

As to adding refrigerant, not good. Leaks often also discharge refrigerant oil. Too much of that and the compresdor will be damaged. Must find and fix the leaks.

89 IMHO has been R12 refrigerant only (check that with the owners manual) and most probably the compressor is not compatible with R134a.

R134a is different and will eat the o-rings and damage the compressor as the refrigerant is not compatible with the oil.
It's smaller molecules and leaks even more through old hoses and seals.

For a proper fix you would need to get the now contaminated R134a out and properly dispose or recycle it, then replace compressor, orifice tube and dessicant. Replace all o-rings (joints) and clean, purge and dry the condenser and the cooling radiator. New oil and new R134a with a new dessicant cartridge.

Else we have a new experiment running on how long an R12 will hold up with R134a.

Just for completeness and for those interested. Have a look at the clean air act and it's regulations
https://www.ecfr.gov/cgi-bin/text-id....82.f&rgn=div6
Title 40: Protection of Environment
PART 82--PROTECTION OF STRATOSPHERIC OZONE
Subpart F--Recycling and Emissions Reduction
§82.154 Prohibitions.
Which in fact simply prohibits any deliberate venting of an ozone layer damaging compound (such as R12) into the atmosphere.

As for the running rough daveca has a point. O2 sensor should definitively be fixed. Does it make any difference in running rough if A/C is "on" or "off"? Most probably unrelated. Is this 89 a TBI injection?

Error, IIRC, R12 &134 have entirely different fittings making it nearly impossible for someone who buys a “homeowner kit” to fill the new stuff into an old system.
OP, did you use one of the ancient hose fittings onto a new can of 134?

Lol I think I still have a full set of r12 guages and a small can quick connect fitting buried in the garage somewhere!

Yep, and the R134a cans come with adapters. The seller is not really into how long his product keeps the thingy alive. Sold is sold.
And the whole HVAC reminds me that I have to order new hoses for the build.