High Blood pressure does not cause fevers or chills. The presence of any infection in the body usually is the most common cause of fever with chills.
As a part of the ongoing process against the infection, many chemical substances are released ( called inflammatory cytokines), the body is under stress and the levels of stress hormones in the blood also increase. These and other conditions may result in an increase in blood pressure. If the infection continues to spread and is not treated, blood pressure may decrease as well- which is not a good sign.
Whenever your father has a fever / chills, you should consult a physician to find the cause and initiate appropriate treatment. After resolution of the fever, check his BP three or four times and then again consult your doctor to decide wether he requires any intervention or not.