When I accelerate from a stop, the engine will start to hesitate when I get to 2500 rpm's. I have replaced the fuel pump, cpi, fuel filter, map sensor, plugs, wires. Don't no what else it could causing this. Runs fine under 2500 rpm. No codes, loose A/C at upper vents when I accelerate. When I keep the gas pedal steady the a/c comes back to the upper vents.

Don't no if I have a leaky fuel pressure regulator or a faulty manifold tuning valve or a bad distributor.

 

What year is your Blazer?

There is a vacuum switch located on the upper driver side of the transfer case that has been known to cause problems with a/c and vents. Transmission fluid is "sucked" up in the vacuum lines in the dash through this switch. What is happening is that the transfer case fluid level is too close to the switch which has a leaking seal that will allow the excess fluid to be "sucked" up into the vacuum lines.

There is a service bulletin at the dealer about this and a new style switch available at the parts counter to fix this problem. But unfortunetly if it has gotten to your a/c, if this is the case, then you may have to replace the switches in the dash that regulate the vents?

As far as the sagging performance above 2500 rpm you should get the codes read to see if there is an issue that the computer is monitoring. You can purchase a scanner or find a place that would read the codes for free. Most people here mention AutoZone for getting the codes read for free.

 

how's the catalytic converter?

 

Budiblazer, please try to have only ONE thread per problem. Currently you have an A/C problem thread, an engine power thread and then this one mentioning both problems.

I am locking this thread as it is a restatement of these two threads (click on links below):
Engine cuts out at 3000 rpm on 95 Blazer
AND
95 blazer a/c stops blowing through upper vents when I accelerate