Question Asked: My Service Engine Soon will come on.
June 27, 2014, 08:47 AM
When I check the system with a scanner at my local mechanic the code that appears is PO420. This car has a 3.1 v6 with automatic transmission. If anyone has encountered the same problem please e-mail any suggestions to correct the problem. Thank you and may you have a Blessed Day.
Question Asked: The AC heater system (hvac)switches to defrost when engine accelerates.
June 20, 2014, 07:19 PM
this problem occurs all the time,the system switches from normal to defrost and back to normal when the fuel petal is released and engine is not being accelerated. I replaced two check valves in vacuum system but still have same problem. Any help will be appreciated. Thank you.
Problem Reported: HVAC Air Flow Switching to Defrost When Accelerating
September 15, 2010, 10:05 PM
<p>The <a id="ce_8277" class="ct_null tooltip" title="Heating and Air Conditioning" href="/heating-ac">AC/heater</a> (HVAC) system may unexpectedly switch to the defrost mode when accelerating. This system is operated by engine vacuum and should be inspected for any vacuum leaks if this problem develops. There is also a revised vacuum check valve available to address this concern.</p>