Infinity 1290: no pressure in pump A


On a Infinity 1290


A) 50% H2O / 30% acetonitrile / 20% isopropanol (v/v/v) containing 10mM ammonium formate

B) 1% H2O / 9% acetonitrile / 90% isopropanol (v/v/v) containing 10mM ammonium formate.

Pump A has been giving pressure problems for the last 2 days but got working after purging, priming, conditioning, and letting it flow for some time.

Today, there is no pressure in pump A. When Pump B is at 100%, all look good. Normal-pressure. As soon as we start giving some %A, the pressure falls.  At 100% A, there is no pressure.

Also, we noticed that purging A, you can see the tubing from the bottle going forward and backward.

I guess some valves need to be cleaned or changed in pump A. What do you suggest?

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